An imaging method using LASERS that is used for mapping subsurface structure. When a reflective site in the sample is at the same optical path length (coherence) as the reference mirror, the detector observes interference fringes.
Tomography using x-ray transmission and a computer algorithm to reconstruct the image.
Imaging methods that result in sharp images of objects located on a chosen plane and blurred images located above or below the plane.
An oval area in the retina, 3 to 5 mm in diameter, usually located temporal to the posterior pole of the eye and slightly below the level of the optic disk. It is characterized by the presence of a yellow pigment diffusely permeating the inner layers, contains the fovea centralis in its center, and provides the best phototropic visual acuity. It is devoid of retinal blood vessels, except in its periphery, and receives nourishment from the choriocapillaris of the choroid. (From Cline et al., Dictionary of Visual Science, 4th ed)
Methods and procedures for the diagnosis of diseases of the eye or of vision disorders.
A view of the world and the individual's environment as comprehensible, manageable, and meaningful, claiming that the way people view their life has a positive influence on their health.
Slender processes of NEURONS, including the AXONS and their glial envelopes (MYELIN SHEATH). Nerve fibers conduct nerve impulses to and from the CENTRAL NERVOUS SYSTEM.
The portion of the optic nerve seen in the fundus with the ophthalmoscope. It is formed by the meeting of all the retinal ganglion cell axons as they enter the optic nerve.
Clarity or sharpness of OCULAR VISION or the ability of the eye to see fine details. Visual acuity depends on the functions of RETINA, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast.
Visualization of a vascular system after intravenous injection of a fluorescein solution. The images may be photographed or televised. It is used especially in studying the retinal and uveal vasculature.
Fluid accumulation in the outer layer of the MACULA LUTEA that results from intraocular or systemic insults. It may develop in a diffuse pattern where the macula appears thickened or it may acquire the characteristic petaloid appearance referred to as cystoid macular edema. Although macular edema may be associated with various underlying conditions, it is most commonly seen following intraocular surgery, venous occlusive disease, DIABETIC RETINOPATHY, and posterior segment inflammatory disease. (From Survey of Ophthalmology 2004; 49(5) 470-90)
Neurons of the innermost layer of the retina, the internal plexiform layer. They are of variable sizes and shapes, and their axons project via the OPTIC NERVE to the brain. A small subset of these cells act as photoreceptors with projections to the SUPRACHIASMATIC NUCLEUS, the center for regulating CIRCADIAN RHYTHM.
The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.
Measurement of distances or movements by means of the phenomena caused by the interference of two rays of light (optical interferometry) or of sound (acoustic interferometry).
Retinal diseases refer to a diverse group of vision-threatening disorders that affect the retina's structure and function, including age-related macular degeneration, diabetic retinopathy, retinal detachment, retinitis pigmentosa, and macular edema, among others.
Conditions which produce injury or dysfunction of the second cranial or optic nerve, which is generally considered a component of the central nervous system. Damage to optic nerve fibers may occur at or near their origin in the retina, at the optic disk, or in the nerve, optic chiasm, optic tract, or lateral geniculate nuclei. Clinical manifestations may include decreased visual acuity and contrast sensitivity, impaired color vision, and an afferent pupillary defect.
Analysis based on the mathematical function first formulated by Jean-Baptiste-Joseph Fourier in 1807. The function, known as the Fourier transform, describes the sinusoidal pattern of any fluctuating pattern in the physical world in terms of its amplitude and its phase. It has broad applications in biomedicine, e.g., analysis of the x-ray crystallography data pivotal in identifying the double helical nature of DNA and in analysis of other molecules, including viruses, and the modified back-projection algorithm universally used in computerized tomography imaging, etc. (From Segen, The Dictionary of Modern Medicine, 1992)
Examination of the interior of the eye with an ophthalmoscope.
LIGHT, it's processes and properties, and the characteristics of materials interacting with it.
An area approximately 1.5 millimeters in diameter within the macula lutea where the retina thins out greatly because of the oblique shifting of all layers except the pigment epithelium layer. It includes the sloping walls of the fovea (clivus) and contains a few rods in its periphery. In its center (foveola) are the cones most adapted to yield high visual acuity, each cone being connected to only one ganglion cell. (Cline et al., Dictionary of Visual Science, 4th ed)
The process of generating three-dimensional images by electronic, photographic, or other methods. For example, three-dimensional images can be generated by assembling multiple tomographic images with the aid of a computer, while photographic 3-D images (HOLOGRAPHY) can be made by exposing film to the interference pattern created when two laser light sources shine on an object.
The front third of the eyeball that includes the structures between the front surface of the cornea and the front of the VITREOUS BODY.
The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.
The concave interior of the eye, consisting of the retina, the choroid, the sclera, the optic disk, and blood vessels, seen by means of the ophthalmoscope. (Cline et al., Dictionary of Visual Science, 4th ed)
An ocular disease, occurring in many forms, having as its primary characteristics an unstable or a sustained increase in the intraocular pressure which the eye cannot withstand without damage to its structure or impairment of its function. The consequences of the increased pressure may be manifested in a variety of symptoms, depending upon type and severity, such as excavation of the optic disk, hardness of the eyeball, corneal anesthesia, reduced visual acuity, seeing of colored halos around lights, disturbed dark adaptation, visual field defects, and headaches. (Dictionary of Visual Science, 4th ed)
An imaging technique using compounds labelled with short-lived positron-emitting radionuclides (such as carbon-11, nitrogen-13, oxygen-15 and fluorine-18) to measure cell metabolism. It has been useful in study of soft tissues such as CANCER; CARDIOVASCULAR SYSTEM; and brain. SINGLE-PHOTON EMISSION-COMPUTED TOMOGRAPHY is closely related to positron emission tomography, but uses isotopes with longer half-lives and resolution is lower.
The thin, highly vascular membrane covering most of the posterior of the eye between the RETINA and SCLERA.
Perforations through the whole thickness of the retina including the macula as the result of inflammation, trauma, degeneration, etc. The concept includes retinal breaks, tears, dialyses, and holes.
Method of measuring and mapping the scope of vision, from central to peripheral of each eye.
Examination of the angle of the anterior chamber of the eye with a specialized optical instrument (gonioscope) or a contact prism lens.
A membrane on the vitreal surface of the retina resulting from the proliferation of one or more of three retinal elements: (1) fibrous astrocytes; (2) fibrocytes; and (3) retinal pigment epithelial cells. Localized epiretinal membranes may occur at the posterior pole of the eye without clinical signs or may cause marked loss of vision as a result of covering, distorting, or detaching the fovea centralis. Epiretinal membranes may cause vascular leakage and secondary retinal edema. In younger individuals some membranes appear to be developmental in origin and occur in otherwise normal eyes. The majority occur in association with retinal holes, ocular concussions, retinal inflammation, or after ocular surgery. (Newell, Ophthalmology: Principles and Concepts, 7th ed, p291)
Descriptive anatomy based on three-dimensional imaging (IMAGING, THREE-DIMENSIONAL) of the body, organs, and structures using a series of computer multiplane sections, displayed by transverse, coronal, and sagittal analyses. It is essential to accurate interpretation by the radiologist of such techniques as ultrasonic diagnosis, MAGNETIC RESONANCE IMAGING, and computed tomography (TOMOGRAPHY, X-RAY COMPUTED). (From Lane & Sharfaei, Modern Sectional Anatomy, 1992, Preface)
Methods of creating machines and devices.
The total area or space visible in a person's peripheral vision with the eye looking straightforward.
The light sensitive outer portion of a retinal rod or a cone photoreceptor cell. The outer segment contains a stack of disk membranes laden with photoreceptive pigments (RETINAL PIGMENTS). The outer segment is connected to the inner segment by a PHOTORECEPTOR CONNECTING CILIUM.
Measurement of the thickness of the CORNEA.
The single layer of pigment-containing epithelial cells in the RETINA, situated closely to the tips (outer segments) of the RETINAL PHOTORECEPTOR CELLS. These epithelial cells are macroglia that perform essential functions for the photoreceptor cells, such as in nutrient transport, phagocytosis of the shed photoreceptor membranes, and ensuring retinal attachment.
The inner portion of a retinal rod or a cone photoreceptor cell, situated between the PHOTORECEPTOR CONNECTING CILIUM and the synapse with the adjacent neurons (RETINAL BIPOLAR CELLS; RETINAL HORIZONTAL CELLS). The inner segment contains the cell body, the nucleus, the mitochondria, and apparatus for protein synthesis.
Tomography using radioactive emissions from injected RADIONUCLIDES and computer ALGORITHMS to reconstruct an image.
Projection of near-IR light (INFRARED RAYS), in the 700-1000 nm region, across an object in parallel beams to an array of sensitive photodetectors. This is repeated at various angles and a mathematical reconstruction provides three dimensional MEDICAL IMAGING of tissues. Based on the relative transparency of tissues to this spectra, it has been used to monitor local oxygenation, brain and joints.
The new and thickened layer of scar tissue that forms on a PROSTHESIS, or as a result of vessel injury especially following ANGIOPLASTY or stent placement.
A scientific tool based on ULTRASONOGRAPHY and used not only for the observation of microstructure in metalwork but also in living tissue. In biomedical application, the acoustic propagation speed in normal and abnormal tissues can be quantified to distinguish their tissue elasticity and other properties.
Improvement of the quality of a picture by various techniques, including computer processing, digital filtering, echocardiographic techniques, light and ultrastructural MICROSCOPY, fluorescence spectrometry and microscopy, scintigraphy, and in vitro image processing at the molecular level.
Devices for examining the interior of the eye, permitting the clear visualization of the structures of the eye at any depth. (UMDNS, 1999)
Disorders of the choroid including hereditary choroidal diseases, neoplasms, and other abnormalities of the vascular layer of the uvea.
Degenerative changes in the RETINA usually of older adults which results in a loss of vision in the center of the visual field (the MACULA LUTEA) because of damage to the retina. It occurs in dry and wet forms.
The pressure of the fluids in the eye.
Detachment of the corpus vitreum (VITREOUS BODY) from its normal attachments, especially the retina, due to shrinkage from degenerative or inflammatory conditions, trauma, myopia, or senility.
Computed tomography where there is continuous X-ray exposure to the patient while being transported in a spiral or helical pattern through the beam of irradiation. This provides improved three-dimensional contrast and spatial resolution compared to conventional computed tomography, where data is obtained and computed from individual sequential exposures.
A specialized field of physics and engineering involved in studying the behavior and properties of light and the technology of analyzing, generating, transmitting, and manipulating ELECTROMAGNETIC RADIATION in the visible, infrared, and ultraviolet range.
The evaluation of incidents involving the loss of function of a device. These evaluations are used for a variety of purposes such as to determine the failure rates, the causes of failures, costs of failures, and the reliability and maintainability of devices.
Instruments for RETINOSCOPY that determines the refractive state of the EYE, such as the degree of NEARSIGHTEDNESS; FARSIGHTEDNESS; or ASTIGMATISM. In principle, a retinoscope provides a light source to illuminate the RETINA, and then locates the aerial image of the retina in space to obtain an index of the refractive quality of the patient's lens system.
Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)
The distance between the anterior and posterior poles of the eye, measured either by ULTRASONOGRAPHY or by partial coherence interferometry.
Separation of the inner layers of the retina (neural retina) from the pigment epithelium. Retinal detachment occurs more commonly in men than in women, in eyes with degenerative myopia, in aging and in aphakia. It may occur after an uncomplicated cataract extraction, but it is seen more often if vitreous humor has been lost during surgery. (Dorland, 27th ed; Newell, Ophthalmology: Principles and Concepts, 7th ed, p310-12).
An exudate between the RETINA and CHOROID from various sources including the vitreous cavity, SUBARACHNOID SPACE, or abnormal vessels.
Excessive axial myopia associated with complications (especially posterior staphyloma and CHOROIDAL NEOVASCULARIZATION) that can lead to BLINDNESS.
A technique of inputting two-dimensional images into a computer and then enhancing or analyzing the imagery into a form that is more useful to the human observer.
Measurement of the index of refraction (the ratio of the velocity of light or other radiation in the first of two media to its velocity in the second as it passes from one into the other).
Disease of the RETINA as a complication of DIABETES MELLITUS. It is characterized by the progressive microvascular complications, such as ANEURYSM, interretinal EDEMA, and intraocular PATHOLOGIC NEOVASCULARIZATION.
A vitreoretinal dystrophy characterized by splitting of the neuroretinal layers. It occurs in two forms: degenerative retinoschisis and X chromosome-linked juvenile retinoschisis.
Recording of electric potentials in the retina after stimulation by light.
Optic disk bodies composed primarily of acid mucopolysaccharides that may produce pseudopapilledema (elevation of the optic disk without associated INTRACRANIAL HYPERTENSION) and visual field deficits. Drusen may also occur in the retina (see RETINAL DRUSEN). (Miller et al., Clinical Neuro-Ophthalmology, 4th ed, p355)
Method of making images on a sensitized surface by exposure to light or other radiant energy.
The space in the eye, filled with aqueous humor, bounded anteriorly by the cornea and a small portion of the sclera and posteriorly by a small portion of the ciliary body, the iris, and that part of the crystalline lens which presents through the pupil. (Cline et al., Dictionary of Visual Science, 4th ed, p109)
The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous CORNEAL EPITHELIUM; BOWMAN MEMBRANE; CORNEAL STROMA; DESCEMET MEMBRANE; and mesenchymal CORNEAL ENDOTHELIUM. It serves as the first refracting medium of the eye. It is structurally continuous with the SCLERA, avascular, receiving its nourishment by permeation through spaces between the lamellae, and is innervated by the ophthalmic division of the TRIGEMINAL NERVE via the ciliary nerves and those of the surrounding conjunctiva which together form plexuses. (Cline et al., Dictionary of Visual Science, 4th ed)
Glaucoma in which the angle of the anterior chamber is open and the trabecular meshwork does not encroach on the base of the iris.
A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.
Colloid or hyaline bodies lying beneath the retinal pigment epithelium. They may occur either secondary to changes in the choroid that affect the pigment epithelium or as an autosomal dominant disorder of the retinal pigment epithelium.
The use of ultrasound to guide minimally invasive surgical procedures such as needle ASPIRATION BIOPSY; DRAINAGE; etc. Its widest application is intravascular ultrasound imaging but it is useful also in urology and intra-abdominal conditions.
A pathological process consisting of the formation of new blood vessels in the CHOROID.
Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.
Removal of the whole or part of the vitreous body in treating endophthalmitis, diabetic retinopathy, retinal detachment, intraocular foreign bodies, and some types of glaucoma.
Types of spiral computed tomography technology in which multiple slices of data are acquired simultaneously improving the resolution over single slice acquisition technology.
Nerve cells of the RETINA in the pathway of transmitting light signals to the CENTRAL NERVOUS SYSTEM. They include the outer layer of PHOTORECEPTOR CELLS, the intermediate layer of RETINAL BIPOLAR CELLS and AMACRINE CELLS, and the internal layer of RETINAL GANGLION CELLS.
Instruments for the visual examination of interior structures of the body. There are rigid endoscopes and flexible fiberoptic endoscopes for various types of viewing in ENDOSCOPY.
Specialized PHOTOTRANSDUCTION neurons in the vertebrates, such as the RETINAL ROD CELLS and the RETINAL CONE CELLS. Non-visual photoreceptor neurons have been reported in the deep brain, the PINEAL GLAND and organs of the circadian system.
The administration of substances into the VITREOUS BODY of the eye with a hypodermic syringe.
Thin strands of transparent material, usually glass, that are used for transmitting light waves over long distances.
General disorders of the sclera or white of the eye. They may include anatomic, embryologic, degenerative, or pigmentation defects.
Methods developed to aid in the interpretation of ultrasound, radiographic images, etc., for diagnosis of disease.
The transparent, semigelatinous substance that fills the cavity behind the CRYSTALLINE LENS of the EYE and in front of the RETINA. It is contained in a thin hyaloid membrane and forms about four fifths of the optic globe.
A method of computed tomography that uses radionuclides which emit a single photon of a given energy. The camera is rotated 180 or 360 degrees around the patient to capture images at multiple positions along the arc. The computer is then used to reconstruct the transaxial, sagittal, and coronal images from the 3-dimensional distribution of radionuclides in the organ. The advantages of SPECT are that it can be used to observe biochemical and physiological processes as well as size and volume of the organ. The disadvantage is that, unlike positron-emission tomography where the positron-electron annihilation results in the emission of 2 photons at 180 degrees from each other, SPECT requires physical collimation to line up the photons, which results in the loss of many available photons and hence degrades the image.
A form of glaucoma in which the intraocular pressure increases because the angle of the anterior chamber is blocked and the aqueous humor cannot drain from the anterior chamber.
Pieces of glass or other transparent materials used for magnification or increased visual acuity.
A form of MACULAR DEGENERATION also known as dry macular degeneration marked by occurrence of a well-defined progressive lesion or atrophy in the central part of the RETINA called the MACULA LUTEA. It is distinguishable from WET MACULAR DEGENERATION in that the latter involves neovascular exudates.
Visual impairments limiting one or more of the basic functions of the eye: visual acuity, dark adaptation, color vision, or peripheral vision. These may result from EYE DISEASES; OPTIC NERVE DISEASES; VISUAL PATHWAY diseases; OCCIPITAL LOBE diseases; OCULAR MOTILITY DISORDERS; and other conditions (From Newell, Ophthalmology: Principles and Concepts, 7th ed, p132).
An objective determination of the refractive state of the eye (NEARSIGHTEDNESS; FARSIGHTEDNESS; ASTIGMATISM). By using a RETINOSCOPE, the amount of correction and the power of lens needed can be determined.
Computed tomography modalities which use a cone or pyramid-shaped beam of radiation.
A tomographic technique for obtaining 3-dimensional images with transmission electron microscopy.
An optical source that emits photons in a coherent beam. Light Amplification by Stimulated Emission of Radiation (LASER) is brought about using devices that transform light of varying frequencies into a single intense, nearly nondivergent beam of monochromatic radiation. Lasers operate in the infrared, visible, ultraviolet, or X-ray regions of the spectrum.
Changes in the observed frequency of waves (as sound, light, or radio waves) due to the relative motion of source and observer. The effect was named for the 19th century Austrian physicist Johann Christian Doppler.
Measurements of the height, weight, length, area, etc., of the human and animal body or its parts.
The veins and arteries of the HEART.
Devices or objects in various imaging techniques used to visualize or enhance visualization by simulating conditions encountered in the procedure. Phantoms are used very often in procedures employing or measuring x-irradiation or radioactive material to evaluate performance. Phantoms often have properties similar to human tissue. Water demonstrates absorbing properties similar to normal tissue, hence water-filled phantoms are used to map radiation levels. Phantoms are used also as teaching aids to simulate real conditions with x-ray or ultrasonic machines. (From Iturralde, Dictionary and Handbook of Nuclear Medicine and Clinical Imaging, 1990)
The failure by the observer to measure or identify a phenomenon accurately, which results in an error. Sources for this may be due to the observer's missing an abnormality, or to faulty technique resulting in incorrect test measurement, or to misinterpretation of the data. Two varieties are inter-observer variation (the amount observers vary from one another when reporting on the same material) and intra-observer variation (the amount one observer varies between observations when reporting more than once on the same material).
The 2nd cranial nerve which conveys visual information from the RETINA to the brain. The nerve carries the axons of the RETINAL GANGLION CELLS which sort at the OPTIC CHIASM and continue via the OPTIC TRACTS to the brain. The largest projection is to the lateral geniculate nuclei; other targets include the SUPERIOR COLLICULI and the SUPRACHIASMATIC NUCLEI. Though known as the second cranial nerve, it is considered part of the CENTRAL NERVOUS SYSTEM.
The use of green light-producing LASERS to stop bleeding. The green light is selectively absorbed by HEMOGLOBIN, thus triggering BLOOD COAGULATION.
A visual impairment characterized by the accumulation of fluid under the retina through a defect in the retinal pigment epithelium.
A technique of diagnostic imaging of RETINA or CORNEA of the human eye involving the measurement and interpretation of polarizing ELECTROMAGNETIC WAVES such as radio or light waves. It is helpful in the diagnosis of GLAUCOMA; MACULAR DEGENERATION; and other retinal disorders.
Measurement of ocular tension (INTRAOCULAR PRESSURE) with a tonometer. (Cline, et al., Dictionary of Visual Science, 4th ed)
The use of statistical and mathematical methods to analyze biological observations and phenomena.
A condition in which the intraocular pressure is elevated above normal and which may lead to glaucoma.
Any visual display of structural or functional patterns of organs or tissues for diagnostic evaluation. It includes measuring physiologic and metabolic responses to physical and chemical stimuli, as well as ultramicroscopy.
Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.
Stents that are covered with materials that are embedded with chemicals that are gradually released into the surrounding milieu.
The property of nonisotropic media, such as crystals, whereby a single incident beam of light traverses the medium as two beams, each plane-polarized, the planes being at right angles to each other. (Cline et al., Dictionary of Visual Science, 4th ed)
Any visible result of a procedure which is caused by the procedure itself and not by the entity being analyzed. Common examples include histological structures introduced by tissue processing, radiographic images of structures that are not naturally present in living tissue, and products of chemical reactions that occur during analysis.
The administration of substances into the eye with a hypodermic syringe.
Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.
Inflammation of the optic nerve. Commonly associated conditions include autoimmune disorders such as MULTIPLE SCLEROSIS, infections, and granulomatous diseases. Clinical features include retro-orbital pain that is aggravated by eye movement, loss of color vision, and contrast sensitivity that may progress to severe visual loss, an afferent pupillary defect (Marcus-Gunn pupil), and in some instances optic disc hyperemia and swelling. Inflammation may occur in the portion of the nerve within the globe (neuropapillitis or anterior optic neuritis) or the portion behind the globe (retrobulbar neuritis or posterior optic neuritis).
A refractive error in which rays of light entering the EYE parallel to the optic axis are brought to a focus in front of the RETINA when accommodation (ACCOMMODATION, OCULAR) is relaxed. This results from an overly curved CORNEA or from the eyeball being too long from front to back. It is also called nearsightedness.
Atrophy of the optic disk which may be congenital or acquired. This condition indicates a deficiency in the number of nerve fibers which arise in the RETINA and converge to form the OPTIC DISK; OPTIC NERVE; OPTIC CHIASM; and optic tracts. GLAUCOMA; ISCHEMIA; inflammation, a chronic elevation of intracranial pressure, toxins, optic nerve compression, and inherited conditions (see OPTIC ATROPHIES, HEREDITARY) are relatively common causes of this condition.
The measurement of curvature and shape of the anterior surface of the cornea using techniques such as keratometry, keratoscopy, photokeratoscopy, profile photography, computer-assisted image processing and videokeratography. This measurement is often applied in the fitting of contact lenses and in diagnosing corneal diseases or corneal changes including keratoconus, which occur after keratotomy and keratoplasty.
A tricarbocyanine dye that is used diagnostically in liver function tests and to determine blood volume and cardiac output.
A form of RETINAL DEGENERATION in which abnormal CHOROIDAL NEOVASCULARIZATION occurs under the RETINA and MACULA LUTEA, causing bleeding and leaking of fluid. This leads to bulging and or lifting of the macula and the distortion or destruction of central vision.
Tomography using x-ray transmission.
Pathological processes of CORONARY ARTERIES that may derive from a congenital abnormality, atherosclerotic, or non-atherosclerotic cause.
The blood vessels which supply and drain the RETINA.
In screening and diagnostic tests, the probability that a person with a positive test is a true positive (i.e., has the disease), is referred to as the predictive value of a positive test; whereas, the predictive value of a negative test is the probability that the person with a negative test does not have the disease. Predictive value is related to the sensitivity and specificity of the test.
Implants constructed of materials designed to be absorbed by the body without producing an immune response. They are usually composed of plastics and are frequently used in orthopedics and orthodontics.
A group of disorders involving predominantly the posterior portion of the ocular fundus, due to degeneration in the sensory layer of the RETINA; RETINAL PIGMENT EPITHELIUM; BRUCH MEMBRANE; CHOROID; or a combination of these tissues.
The most anterior portion of the uveal layer, separating the anterior chamber from the posterior. It consists of two layers - the stroma and the pigmented epithelium. Color of the iris depends on the amount of melanin in the stroma on reflection from the pigmented epithelium.
Hereditary, progressive degeneration of the neuroepithelium of the retina characterized by night blindness and progressive contraction of the visual field.
The technology of transmitting light over long distances through strands of glass or other transparent material.
Lesions formed within the walls of ARTERIES.
An esterified form of TRIAMCINOLONE. It is an anti-inflammatory glucocorticoid used topically in the treatment of various skin disorders. Intralesional, intramuscular, and intra-articular injections are also administered under certain conditions.
Surgical removal of a section of the iris.
A retrogressive pathological change in the retina, focal or generalized, caused by genetic defects, inflammation, trauma, vascular disease, or aging. Degeneration affecting predominantly the macula lutea of the retina is MACULAR DEGENERATION. (Newell, Ophthalmology: Principles and Concepts, 7th ed, p304)
The use of instrumentation and techniques for visualizing material and details that cannot be seen by the unaided eye. It is usually done by enlarging images, transmitted by light or electron beams, with optical or magnetic lenses that magnify the entire image field. With scanning microscopy, images are generated by collecting output from the specimen in a point-by-point fashion, on a magnified scale, as it is scanned by a narrow beam of light or electrons, a laser, a conductive probe, or a topographical probe.
Radiography of the vascular system of the heart muscle after injection of a contrast medium.
Refraction of LIGHT effected by the media of the EYE.
A surgical procedure or KERATOPLASTY involving selective stripping and replacement of diseased host DESCEMET MEMBRANE and CORNEAL ENDOTHELIUM with a suitable and healthy donor posterior lamella. The advantage to this procedure is that the normal corneal surface of the recipient is retained, thereby avoiding corneal surface incisions and sutures.
Studies to determine the advantages or disadvantages, practicability, or capability of accomplishing a projected plan, study, or project.
The white, opaque, fibrous, outer tunic of the eyeball, covering it entirely excepting the segment covered anteriorly by the cornea. It is essentially avascular but contains apertures for vessels, lymphatics, and nerves. It receives the tendons of insertion of the extraocular muscles and at the corneoscleral junction contains the canal of Schlemm. (From Cline et al., Dictionary of Visual Science, 4th ed)
Blockage of the RETINAL VEIN. Those at high risk for this condition include patients with HYPERTENSION; DIABETES MELLITUS; ATHEROSCLEROSIS; and other CARDIOVASCULAR DISEASES.
Elements of limited time intervals, contributing to particular results or situations.
An excessive amount of fluid in the cornea due to damage of the epithelium or endothelium causing decreased visual acuity.
Microscopy using polarized light in which phenomena due to the preferential orientation of optical properties with respect to the vibration plane of the polarized light are made visible and correlated parameters are made measurable.
Behavior of LIGHT and its interactions with itself and materials.
Specialized ophthalmic technique used in the surgical repair and or treatment of disorders that include retinal tears or detachment; MACULAR HOLES; hereditary retinal disease; AIDS-related retinal infections; ocular tumors; MACULAR DEGENERATION; DIABETIC RETINOPATHY; and UVEITIS.
A graphic means for assessing the ability of a screening test to discriminate between healthy and diseased persons; may also be used in other studies, e.g., distinguishing stimuli responses as to a faint stimuli or nonstimuli.
The compound is given by intravenous injection to do POSITRON-EMISSION TOMOGRAPHY for the assessment of cerebral and myocardial glucose metabolism in various physiological or pathological states including stroke and myocardial ischemia. It is also employed for the detection of malignant tumors including those of the brain, liver, and thyroid gland. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1162)
Nonionic surfactant mixtures varying in the number of repeating ethoxy (oxy-1,2-ethanediyl) groups. They are used as detergents, emulsifiers, wetting agents, defoaming agents, etc. Nonoxynol-9, the compound with 9 repeating ethoxy groups, is a spermatocide, formulated primarily as a component of vaginal foams and creams.
Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.
The range or frequency distribution of a measurement in a population (of organisms, organs or things) that has not been selected for the presence of disease or abnormality.
A macrolide compound obtained from Streptomyces hygroscopicus that acts by selectively blocking the transcriptional activation of cytokines thereby inhibiting cytokine production. It is bioactive only when bound to IMMUNOPHILINS. Sirolimus is a potent immunosuppressant and possesses both antifungal and antineoplastic properties.
The use of computers for designing and/or manufacturing of anything, including drugs, surgical procedures, orthotics, and prosthetics.
Swelling of the OPTIC DISK, usually in association with increased intracranial pressure, characterized by hyperemia, blurring of the disk margins, microhemorrhages, blind spot enlargement, and engorgement of retinal veins. Chronic papilledema may cause OPTIC ATROPHY and visual loss. (Miller et al., Clinical Neuro-Ophthalmology, 4th ed, p175)
A noninflammatory, usually bilateral protrusion of the cornea, the apex being displaced downward and nasally. It occurs most commonly in females at about puberty. The cause is unknown but hereditary factors may play a role. The -conus refers to the cone shape of the corneal protrusion. (From Dorland, 27th ed)
A surgical procedure to correct MYOPIA by CORNEAL STROMA subtraction. It involves the use of a microkeratome to make a lamellar dissection of the CORNEA creating a flap with intact CORNEAL EPITHELIUM. After the flap is lifted, the underlying midstroma is reshaped with an EXCIMER LASER and the flap is returned to its original position.
X-ray image-detecting devices that make a focused image of body structures lying in a predetermined plane from which more complex images are computed.
Computer-assisted processing of electric, ultrasonic, or electronic signals to interpret function and activity.
Exudates are fluids, CELLS, or other cellular substances that are slowly discharged from BLOOD VESSELS usually from inflamed tissues. Transudates are fluids that pass through a membrane or squeeze through tissue or into the EXTRACELLULAR SPACE of TISSUES. Transudates are thin and watery and contain few cells or PROTEINS.
Studies in which the presence or absence of disease or other health-related variables are determined in each member of the study population or in a representative sample at one particular time. This contrasts with LONGITUDINAL STUDIES which are followed over a period of time.
The inner layer of CHOROID, also called the lamina basalis choroideae, located adjacent to the RETINAL PIGMENT EPITHELIUM; (RPE) of the EYE. It is a membrane composed of the basement membranes of the choriocapillaris ENDOTHELIUM and that of the RPE. The membrane stops at the OPTIC NERVE, as does the RPE.
Investigative and diagnostic methods and procedures based on the photoacoustic effect, which is the generation of SOUND WAVES from the absorption of ELECTROMAGNETIC RADIATION.
A procedure for removal of the crystalline lens in cataract surgery in which an anterior capsulectomy is performed by means of a needle inserted through a small incision at the temporal limbus, allowing the lens contents to fall through the dilated pupil into the anterior chamber where they are broken up by the use of ultrasound and aspirated out of the eye through the incision. (Cline, et al., Dictionary of Visual Science, 4th ed & In Focus 1993;1(1):1)
The diversion of RADIATION (thermal, electromagnetic, or nuclear) from its original path as a result of interactions or collisions with atoms, molecules, or larger particles in the atmosphere or other media. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
Autosomal dominant hereditary maculopathy with childhood-onset accumulation of LIPOFUSION in RETINAL PIGMENT EPITHELIUM. Affected individuals develop progressive central acuity loss, and distorted vision (METAMORPHOPSIA). It is associated with mutations in bestrophin, a chloride channel.
Pathologic changes that occur in the axon and cell body of a neuron proximal to an axonal lesion. The process is characterized by central chromatolysis which features flattening and displacement of the nucleus, loss of Nissl bodies, and cellular edema. Central chromatolysis primarily occurs in lower motor neurons.
A layer of acellular matrix that lies beneath the CORNEAL EPITHELIUM and above the CORNEAL STROMA. It consists of randomly arranged COLLAGEN fibers in a condensed bed of intercellular substance. It provides stability and strength to the cornea.
Devices that provide support for tubular structures that are being anastomosed or for body cavities during skin grafting.
Agents that affect the rate or intensity of cardiac contraction, blood vessel diameter, or blood volume.
Coagulation of blood in any of the CORONARY VESSELS. The presence of a blood clot (THROMBUS) often leads to MYOCARDIAL INFARCTION.
The fluid secreted by the lacrimal glands. This fluid moistens the CONJUNCTIVA and CORNEA.
A localized defect in the visual field bordered by an area of normal vision. This occurs with a variety of EYE DISEASES (e.g., RETINAL DISEASES and GLAUCOMA); OPTIC NERVE DISEASES, and other conditions.
Surgical techniques on the CORNEA employing LASERS, especially for reshaping the CORNEA to correct REFRACTIVE ERRORS.
Production of a radiographic image of a small or very thin object on fine-grained photographic film under conditions which permit subsequent microscopic examination or enlargement of the radiograph at linear magnifications of up to several hundred and with a resolution approaching the resolving power of the photographic emulsion (about 1000 lines per millimeter).
A tooth's loss of minerals, such as calcium in hydroxyapatite from the tooth matrix, caused by acidic exposure. An example of the occurrence of demineralization is in the formation of dental caries.
Soft, supple contact lenses made of plastic polymers which interact readily with water molecules. Many types are available, including continuous and extended-wear versions, which are gas-permeable and easily sterilized.
Recurrent narrowing or constriction of a coronary artery following surgical procedures performed to alleviate a prior obstruction.
Surgery performed on the eye or any of its parts.
Endoscopes for examining the interior of the esophagus.
Diagnostic tests conducted in order to measure the increment of active DENTAL CARIES over a period of time.
Narrowing or constriction of a coronary artery.
Dilation of an occluded coronary artery (or arteries) by means of a balloon catheter to restore myocardial blood supply.
A layer of the cornea. It is the basal lamina of the CORNEAL ENDOTHELIUM (from which it is secreted) separating it from the CORNEAL STROMA. It is a homogeneous structure composed of fine collagenous filaments, and slowly increases in thickness with age.
Small-scale tests of methods and procedures to be used on a larger scale if the pilot study demonstrates that these methods and procedures can work.
Levels within a diagnostic group which are established by various measurement criteria applied to the seriousness of a patient's disorder.
A form of GLAUCOMA in which chronic optic nerve damage and loss of vision normally attributable to buildup of intraocular pressure occurs despite prevailing conditions of normal intraocular pressure.
Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.
The plan and delineation of prostheses in general or a specific prosthesis.
A group of rare, idiopathic, congenital retinal vascular anomalies affecting the retinal capillaries. It is characterized by dilation and tortuosity of retinal vessels and formation of multiple aneurysms, with different degrees of leakage and exudates emanating from the blood vessels.
Ischemic injury to the OPTIC NERVE which usually affects the OPTIC DISK (optic neuropathy, anterior ischemic) and less frequently the retrobulbar portion of the nerve (optic neuropathy, posterior ischemic). The injury results from occlusion of arterial blood supply which may result from TEMPORAL ARTERITIS; ATHEROSCLEROSIS; COLLAGEN DISEASES; EMBOLISM; DIABETES MELLITUS; and other conditions. The disease primarily occurs in the sixth decade or later and presents with the sudden onset of painless and usually severe monocular visual loss. Anterior ischemic optic neuropathy also features optic disk edema with microhemorrhages. The optic disk appears normal in posterior ischemic optic neuropathy. (Glaser, Neuro-Ophthalmology, 2nd ed, p135)
Endoscopic examination, therapy or surgery performed on the interior of blood vessels.
Introduction of substances into the body using a needle and syringe.
That portion of the electromagnetic spectrum usually sensed as heat. Infrared wavelengths are longer than those of visible light, extending into the microwave frequencies. They are used therapeutically as heat, and also to warm food in restaurants.
Substances used to allow enhanced visualization of tissues.
Tear or break of an organ, vessel or other soft part of the body, occurring in the absence of external force.
Agents and endogenous substances that antagonize or inhibit the development of new blood vessels.
The comparison of the quantity of meaningful data to the irrelevant or incorrect data.
Photosensitive afferent neurons located primarily within the FOVEA CENTRALIS of the MACULA LUTEA. There are three major types of cone cells (red, blue, and green) whose photopigments have different spectral sensitivity curves. Retinal cone cells operate in daylight vision (at photopic intensities) providing color recognition and central visual acuity.
The X-shaped structure formed by the meeting of the two optic nerves. At the optic chiasm the fibers from the medial part of each retina cross to project to the other side of the brain while the lateral retinal fibers continue on the same side. As a result each half of the brain receives information about the contralateral visual field from both eyes.
The aperture in the iris through which light passes.
The protrusion of an organ or part of an organ into a natural or artificial orifice.
That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.
Permanent dilation of preexisting blood vessels (CAPILLARIES; ARTERIOLES; VENULES) creating small focal red lesions, most commonly in the skin or mucous membranes. It is characterized by the prominence of skin blood vessels, such as vascular spiders.
A family of percutaneous techniques that are used to manage CORONARY OCCLUSION, including standard balloon angioplasty (PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY), the placement of intracoronary STENTS, and atheroablative technologies (e.g., ATHERECTOMY; ENDARTERECTOMY; THROMBECTOMY; PERCUTANEOUS TRANSLUMINAL LASER ANGIOPLASTY). PTCA was the dominant form of PCI, before the widespread use of stenting.
Chemical substances that are destructive to spermatozoa used as topically administered vaginal contraceptives.
Transmission of gene defects or chromosomal aberrations/abnormalities which are expressed in extreme variation in the structure or function of the eye. These may be evident at birth, but may be manifested later with progression of the disorder.
An X chromosome-linked abnormality characterized by atrophy of the choroid and degeneration of the retinal pigment epithelium causing night blindness.

Intravascular modalities for detection of vulnerable plaque: current status. (1/2999)

Progress in the diagnosis, treatment, and prevention of atherosclerotic coronary artery disease is dependent on a greater understanding of the mechanisms of coronary plaque progression. Autopsy studies have characterized a subgroup of high-risk, or vulnerable, plaques that result in acute coronary syndromes or sudden cardiac death. These angiographically modest plaques share certain pathologic characteristics: a thin, fibrous cap, lipid-rich core, and macrophage activity. Diagnostic techniques for vulnerable-plaque detection, including serologic markers and noninvasive and invasive techniques, are needed. Recent advances in intravascular imaging have significantly improved the ability to detect high-risk, or vulnerable, plaque in vivo by using various features of plaque vulnerability as methods of identification. The characteristic anatomy of a thin, fibrous cap overlying a lipid pool has promoted high-resolution imaging, such as intravascular ultrasound, optical coherence tomography, and intracoronary magnetic resonance. The lipid-rich core is identifiable by angioscopically detected color changes on the plaque surface or by its unique absorption of energy, or "Raman shift," of its cholesterol core, driving coronary spectroscopy. Finally, temperature heterogeneity arising at foci of plaque inflammation has prompted the development of intracoronary thermography. In this review, we will discuss these techniques, their relative advantages and limitations, and their potential clinical application.  (+info)

Choroidal neovascularization characteristics and its size in optical coherence tomography. (2/2999)

The classification, size and activity of choroidal neovascularization (CNV) by optical coherence tomography (OCT) were compared with those obtained by fluorescein angiography (FA) and Indocyanine green angiography (ICG). This study included 32 patients (32 eyes) diagnosed as having CNV. The etiology of CNV was found to be age-related macular degeneration (AMD) or non-AMD. Patients were studied retrospectively by FA, ICG, and OCT. Of the 13 eyes with AMD, the boundary of the lesion could not be defined using FA in 7 patients. Among the 7 poorly defined CNV cases by FA, the identification of the boundary was possible in one case by OCT. The mean diameter of the classic well-defined lesions was 3500 +/- 421 microm by FA, 2624 +/- 1044 microm by ICG, and 1927 +/- 1272 microm by OCT. The size of the CNV by OCT was always smaller than by FA or ICG. Of the 19 eyes with Non-AMD, the boundary of the lesion could not be defined by FA in 5 patients. Among the 5 poorly defined cases by FA, the identification of the boundary was possible in 3 cases by OCT. The mean diameter of the well-defined CNV lesions was 2153 +/- 759 microm by FA, 1929 +/- 673 microm by ICG, and 1322 +/- 566 microm by OCT. Retinal thickness, which represents retinal edema, was found to be proportional to lesion size, although the relationship was not statistically significant. Regardless of CNV type, FA, ICG and OCT used in combination increase the specificity of diagnosis if their findings are compared.  (+info)

Optical imaging of the cervix. (3/2999)

Recent advances in fiber optics, sources and detectors, imaging, and computer-controlled instrumentation have stimulated a period of unprecedented growth in the development of photonics technologies for a wide variety of diagnostic and therapeutic clinical applications. These include the application of quantitative optical spectroscopy and imaging for the detection of precancerous lesions in the uterine cervix, a topic of interest at the Second International Conference on Cervical Cancer, which was held April 11-14, 2002. Investigators have applied the Littenberg method of emerging technology assessment to new optical methods used to detect cervical neoplasia. Currently, such technologies as fluorescence spectroscopy (the combination of fluorescence and diffuse reflectance spectroscopy), tri-modal spectroscopy, and light-scattering spectroscopy that probe the spectral characteristics of tissue are being investigated. Optical technologies that create images of subcellular structure without biopsy subsequent to pathology that currently are under investigation include in vivo confocal imaging and optical coherence tomography. Numerous small studies have demonstrated the potential of these optical technologies. What remains to be elucidated are the fundamental biophysical origins of variations in remitted optical signals between normal and dysplastic tissue. Large multicenter randomized controlled trials are needed to confirm the detection and imaging capabilities of optical technology. Furthermore, the development of contrast agents that could boost detection with these technologies is needed, and basic biologic characterization of signals should be pursued. Applying the Littenberg assessment will help ensure that superior, not simply alternative, technologies are implemented.  (+info)

Optical coherence tomography disc assessment in optic nerves with peripapillary atrophy. (4/2999)

BACKGROUND AND OBJECTIVE: Optical coherence tomography (OCT) is able to determine the optic disc margin automatically. The aim of this study was to investigate the accuracy of the automatic OCT optic nerve head measurements in the presence of peripapillary atrophy. PATIENTS AND METHODS: This was a cross-sectional, retrospective study. Thirty-one subjects with peripapillary atrophy underwent optic nerve head scanning with OCT version 3. Nineteen of the eyes were classified clinically as having glaucoma, nine had suspected glaucoma, and three were normal. Automatic OCT results were compared with manual tracing results. RESULTS: Significant differences were found between most OCT optic nerve head automated and manual disc assessment parameters; however, good agreement was found between the two methods for all parameters (intraclass correlation, 0.71 to 0.94). Areas under receiver operator characteristics curves for clinical status were similar for all parameters with both methods. CONCLUSION: Automated OCT optic nerve head analysis may be used in the clinical setting in the presence of peripapillary atrophy; however, caution should be used when comparing individual results with population-derived optic nerve head results.  (+info)

Delayed regeneration of foveal cone photopigments in Vogt-Koyanagi-Harada disease at the convalescent stage. (5/2999)

PURPOSE: To evaluate the physiological characteristics of the macula in patients with Vogt-Koyanagi-Harada disease during the convalescent stage with specific reference to the kinetics of foveal cone photopigment regeneration. METHODS: Six eyes of three patients at the convalescent stage of Vogt-Koyanagi-Harada disease were studied. All the eyes had best corrected visual acuity of 1.0 or better and had had no recurrence of inflammation for at least 12 months after the last episode. Foveal cone densitometry (FCD), focal macular electroretinograms, color vision tests, two-color perimetry, and optical coherence tomography (OCT) were performed. RESULTS: No regeneration of cone photopigments was detected within the 7-minute testing time by FCD in all eyes at the first examination after the last episode. However, the other functional tests were normal, and the OCT-determined macular morphology was also normal. The regeneration kinetics of the foveal cone photopigment improved in three of six eyes at 36, 37, and 19 months after the last episode, whereas the other three remained delayed at 18, 18, and 49 months. CONCLUSIONS: These findings suggest that a disorder of the foveal cone photopigment regeneration, and its recovery, requires a significantly longer time than that of other macular functions in some patients with Vogt-Koyanagi-Harada disease.  (+info)

Secondary retinal changes associated with choroidal naevi and melanomas documented by optical coherence tomography. (6/2999)

AIMS: To establish the characteristics of secondary retinal changes associated with the presence of choroidal melanomas and choroidal naevi as documented by optical coherence tomography (OCT). METHODS: Twenty patients with untreated choroidal melanoma and 40 patients with presumed choroidal naevi managed by regular observation were included in the study. OCT scans across the surface of the tumour and surrounding tissue were acquired for all participants. The appearance of retinal tissue on the OCT scans was considered to be abnormal if it did not display the well defined band structure characteristic of normal tissue on OCT scans. RESULTS: Serous retinal detachments were observed in all patients with choroidal melanoma and 18 out of 20 also had abnormal retinal structure or intra-retinal splitting in the tissue overlying the tumour. Out of the 40 patients with presumed choroidal naevi, 12 had serous detachments and three had either abnormal retinal structure or intra-retinal splitting overlying the lesion. CONCLUSIONS: Secondary retinal changes associated with choroidal lesions can be documented by OCT. These changes were observed in most patients with choroidal melanoma included in the study group but were far less prevalent in the patients with presumed choroidal naevi. OCT is also able to identify the presence of small serous detachments before they become clinically visible. Follow up of these patients is required to determine whether the OCT results may be of use in the differential diagnosis of small choroidal lesions.  (+info)

Onset of pulsatile pressure causes transiently increased filtration through artery wall. (7/2999)

Convective fluid motion through artery walls aids in the transvascular transport of macromolecules. Although many measurements of convective filtration have been reported, they were all obtained under constant transmural pressure. However, arterial pressure in vivo is pulsatile. Therefore, experiments were designed to compare filtration under steady and pulsatile pressure conditions. Rabbit carotid arteries were cannulated and excised from male New Zealand White rabbits anesthetized with pentobarbitol sodium (30 mg/kg i.v. administered). Hydraulic conductance was measured in cannulated excised rabbit carotid arteries at steady pressure. Next, pulsatile pressure trains were applied within the same vessels, and, simultaneously, arterial distension was monitored using Optical coherence tomography (OCT). For each pulse train, the volume of fluid lost through filtration was measured (subtracting volume change due to residual distension) and compared with that predicted from steady pressure measurements. At 60- and 80-mmHg baseline pressures, the experimental filtration volumes were significantly increased compared with those predicted for steady pressure (P < 0.05). OCT demonstrated that the excess fluid volume loss was significantly greater than the volume that would be lost through residual distension (P < 0.05). After 30 s, the magnitude of the excess of fluid loss was reduced. These results suggest that sudden onset of pulsatile pressure may cause changes in arterial interstitial hydration.  (+info)

Supplemental oxygen improves diabetic macular edema: a pilot study. (8/2999)

PURPOSE: Diabetic macular edema (DME) is the most common cause of moderate visual disability in persons of working age in the United States. The pathogenesis of DME is poorly understood. In this study, the effect of retinal hypoxia in the development and maintenance of DME was investigated. METHODS: Five patients with chronic DME despite at least one focal laser photocoagulation treatment (nine eyes) received 4 L/min of inspired oxygen by nasal cannula for 3 months. Best corrected visual acuity (VA) and retinal thickness, assessed by optical coherence tomography (OCT), were measured at baseline, during 3 months of oxygen treatment, and for 3 months after stopping oxygen. RESULTS: After 3 months of oxygen therapy, nine of nine eyes with DME at baseline showed a reduction in thickness of the center of the macula. Foveal thickness (FTH) above the normal range was reduced by an average of 43.5% (range, 14%-100%), excess foveolar thickness (CEN) was reduced by an average of 42.1% (range, 13%-100%), and excess macular volume was reduced by an average of 54% (range, 35%-100%). Statistical analyses suggested that these changes were unlikely to be due to chance (P = 0.0077 by Wilcoxon signed-rank test). Three eyes showed improvement in VA by at least 2 lines, one by slightly less than 2 lines, and five eyes showed no change. Three months after discontinuation of oxygen, five of the nine eyes showed increased thickening of the macula compared with when oxygen was discontinued. CONCLUSIONS: Supplemental inspired oxygen may decrease macular thickness due to DME, suggesting that retinal hypoxia is involved in the development and maintenance of DME.  (+info)

Optical coherence tomography (OCT) is a non-invasive imaging technique that uses low-coherence light to capture high-resolution cross-sectional images of biological tissues, particularly the retina and other ocular structures. OCT works by measuring the echo time delay of light scattered back from different depths within the tissue, creating a detailed map of the tissue's structure. This technique is widely used in ophthalmology to diagnose and monitor various eye conditions such as macular degeneration, diabetic retinopathy, and glaucoma.

X-ray computed tomography (CT or CAT scan) is a medical imaging method that uses computer-processed combinations of many X-ray images taken from different angles to produce cross-sectional (tomographic) images (virtual "slices") of the body. These cross-sectional images can then be used to display detailed internal views of organs, bones, and soft tissues in the body.

The term "computed tomography" is used instead of "CT scan" or "CAT scan" because the machines take a series of X-ray measurements from different angles around the body and then use a computer to process these data to create detailed images of internal structures within the body.

CT scanning is a noninvasive, painless medical test that helps physicians diagnose and treat medical conditions. CT imaging provides detailed information about many types of tissue including lung, bone, soft tissue and blood vessels. CT examinations can be performed on every part of the body for a variety of reasons including diagnosis, surgical planning, and monitoring of therapeutic responses.

In computed tomography (CT), an X-ray source and detector rotate around the patient, measuring the X-ray attenuation at many different angles. A computer uses this data to construct a cross-sectional image by the process of reconstruction. This technique is called "tomography". The term "computed" refers to the use of a computer to reconstruct the images.

CT has become an important tool in medical imaging and diagnosis, allowing radiologists and other physicians to view detailed internal images of the body. It can help identify many different medical conditions including cancer, heart disease, lung nodules, liver tumors, and internal injuries from trauma. CT is also commonly used for guiding biopsies and other minimally invasive procedures.

In summary, X-ray computed tomography (CT or CAT scan) is a medical imaging technique that uses computer-processed combinations of many X-ray images taken from different angles to produce cross-sectional images of the body. It provides detailed internal views of organs, bones, and soft tissues in the body, allowing physicians to diagnose and treat medical conditions.

Tomography is a medical imaging technique used to produce cross-sectional images or slices of specific areas of the body. This technique uses various forms of radiation (X-rays, gamma rays) or sound waves (ultrasound) to create detailed images of the internal structures, such as organs, bones, and tissues. Common types of tomography include Computerized Tomography (CT), Positron Emission Tomography (PET), and Magnetic Resonance Imaging (MRI). The primary advantage of tomography is its ability to provide clear and detailed images of internal structures, allowing healthcare professionals to accurately diagnose and monitor a wide range of medical conditions.

The macula lutea, often simply referred to as the macula or fovea centralis, is a part of the eye that is responsible for central vision and color perception. It's located in the center of the retina, the light-sensitive tissue at the back of the eye. The macula contains a high concentration of pigments called xanthophylls, which give it a yellowish color and protect the photoreceptor cells in this area from damage by blue light.

The central part of the macula is called the fovea, which is a small depression that contains only cones, the photoreceptor cells responsible for color vision and high visual acuity. The fovea is surrounded by the parafovea and the perifovea, which contain both cones and rods, the photoreceptor cells responsible for low-light vision and peripheral vision.

Damage to the macula can result in a loss of central vision and color perception, a condition known as age-related macular degeneration (AMD), which is a leading cause of blindness in older adults. Other conditions that can affect the macula include macular edema, macular holes, and macular pucker.

Diagnostic techniques in ophthalmology refer to the various methods and tests used by eye specialists (ophthalmologists) to examine, evaluate, and diagnose conditions related to the eyes and visual system. Here are some commonly used diagnostic techniques:

1. Visual Acuity Testing: This is a basic test to measure the sharpness of a person's vision. It typically involves reading letters or numbers from an eye chart at a specific distance.
2. Refraction Test: This test helps determine the correct lens prescription for glasses or contact lenses by measuring how light is bent as it passes through the cornea and lens.
3. Slit Lamp Examination: A slit lamp is a microscope that allows an ophthalmologist to examine the structures of the eye, including the cornea, iris, lens, and retina, in great detail.
4. Tonometry: This test measures the pressure inside the eye (intraocular pressure) to detect conditions like glaucoma. Common methods include applanation tonometry and non-contact tonometry.
5. Retinal Imaging: Several techniques are used to capture images of the retina, including fundus photography, fluorescein angiography, and optical coherence tomography (OCT). These tests help diagnose conditions like macular degeneration, diabetic retinopathy, and retinal detachments.
6. Color Vision Testing: This test evaluates a person's ability to distinguish between different colors, which can help detect color vision deficiencies or neurological disorders affecting the visual pathway.
7. Visual Field Testing: This test measures a person's peripheral (or side) vision and can help diagnose conditions like glaucoma, optic nerve damage, or brain injuries.
8. Pupillary Reactions Tests: These tests evaluate how the pupils respond to light and near objects, which can provide information about the condition of the eye's internal structures and the nervous system.
9. Ocular Motility Testing: This test assesses eye movements and alignment, helping diagnose conditions like strabismus (crossed eyes) or nystagmus (involuntary eye movement).
10. Corneal Topography: This non-invasive imaging technique maps the curvature of the cornea, which can help detect irregularities, assess the fit of contact lenses, and plan refractive surgery procedures.

The "Sense of Coherence" (SOC) is a theoretical concept in the field of medical and psychological science, which refers to an individual's global orientation towards their own life and the stimuli they encounter in it. It is not a medical diagnosis or a specific symptom, but rather a measure of an individual's resilience and ability to cope with stressors and adversity.

The SOC is typically measured using a questionnaire developed by Aaron Antonovsky, and it consists of three components: comprehensibility, manageability, and meaningfulness. Comprehensibility refers to the extent to which one perceives their environment and experiences as making cognitive sense, or being predictable and explicable. Manageability refers to the belief that resources are available to meet the demands posed by these experiences. Meaningfulness refers to the motivation to invest energy in dealing with the challenges of life, and the belief that such efforts are worthwhile.

A strong SOC has been associated with better health outcomes, including lower levels of depression and anxiety, better quality of life, and improved coping skills. It is thought to act as a buffer against stress and adversity, helping individuals to maintain their physical and mental well-being in the face of challenging circumstances.

Nerve fibers are specialized structures that constitute the long, slender processes (axons) of neurons (nerve cells). They are responsible for conducting electrical impulses, known as action potentials, away from the cell body and transmitting them to other neurons or effector organs such as muscles and glands. Nerve fibers are often surrounded by supportive cells called glial cells and are grouped together to form nerve bundles or nerves. These fibers can be myelinated (covered with a fatty insulating sheath called myelin) or unmyelinated, which influences the speed of impulse transmission.

The optic disk, also known as the optic nerve head, is the point where the optic nerve fibers exit the eye and transmit visual information to the brain. It appears as a pale, circular area in the back of the eye, near the center of the retina. The optic disk has no photoreceptor cells (rods and cones), so it is insensitive to light. It is an important structure to observe during eye examinations because changes in its appearance can indicate various ocular diseases or conditions, such as glaucoma, optic neuritis, or papilledema.

Visual acuity is a measure of the sharpness or clarity of vision. It is usually tested by reading an eye chart from a specific distance, such as 20 feet (6 meters). The standard eye chart used for this purpose is called the Snellen chart, which contains rows of letters that decrease in size as you read down the chart.

Visual acuity is typically expressed as a fraction, with the numerator representing the testing distance and the denominator indicating the smallest line of type that can be read clearly. For example, if a person can read the line on the eye chart that corresponds to a visual acuity of 20/20, it means they have normal vision at 20 feet. If their visual acuity is 20/40, it means they must be as close as 20 feet to see what someone with normal vision can see at 40 feet.

It's important to note that visual acuity is just one aspect of overall vision and does not necessarily reflect other important factors such as peripheral vision, depth perception, color vision, or contrast sensitivity.

Fluorescein angiography is a medical diagnostic procedure used in ophthalmology to examine the blood flow in the retina and choroid, which are the inner layers of the eye. This test involves injecting a fluorescent dye, Fluorescein, into a patient's arm vein. As the dye reaches the blood vessels in the eye, a specialized camera takes rapid sequences of photographs to capture the dye's circulation through the retina and choroid.

The images produced by fluorescein angiography can help doctors identify any damage to the blood vessels, leakage, or abnormal growth of new blood vessels. This information is crucial in diagnosing and managing various eye conditions such as age-related macular degeneration, diabetic retinopathy, retinal vein occlusions, and inflammatory eye diseases.

It's important to note that while fluorescein angiography is a valuable diagnostic tool, it does carry some risks, including temporary side effects like nausea, vomiting, or allergic reactions to the dye. In rare cases, severe adverse reactions can occur, so patients should discuss these potential risks with their healthcare provider before undergoing the procedure.

Macular edema is a medical condition characterized by the accumulation of fluid in the macula, a small area in the center of the retina responsible for sharp, detailed vision. This buildup of fluid causes the macula to thicken and swell, which can distort central vision and lead to vision loss if not treated promptly. Macular edema is often a complication of other eye conditions such as diabetic retinopathy, age-related macular degeneration, retinal vein occlusion, or uveitis. It's important to note that while macular edema can affect anyone, it is more common in people with certain medical conditions like diabetes.

Retinal Ganglion Cells (RGCs) are a type of neuron located in the innermost layer of the retina, the light-sensitive tissue at the back of the eye. These cells receive visual information from photoreceptors (rods and cones) via intermediate cells called bipolar cells. RGCs then send this visual information through their long axons to form the optic nerve, which transmits the signals to the brain for processing and interpretation as vision.

There are several types of RGCs, each with distinct morphological and functional characteristics. Some RGCs are specialized in detecting specific features of the visual scene, such as motion, contrast, color, or brightness. The diversity of RGCs allows for a rich and complex representation of the visual world in the brain.

Damage to RGCs can lead to various visual impairments, including loss of vision, reduced visual acuity, and altered visual fields. Conditions associated with RGC damage or degeneration include glaucoma, optic neuritis, ischemic optic neuropathy, and some inherited retinal diseases.

The retina is the innermost, light-sensitive layer of tissue in the eye of many vertebrates and some cephalopods. It receives light that has been focused by the cornea and lens, converts it into neural signals, and sends these to the brain via the optic nerve. The retina contains several types of photoreceptor cells including rods (which handle vision in low light) and cones (which are active in bright light and are capable of color vision).

In medical terms, any pathological changes or diseases affecting the retinal structure and function can lead to visual impairment or blindness. Examples include age-related macular degeneration, diabetic retinopathy, retinal detachment, and retinitis pigmentosa among others.

Interferometry is not specifically a medical term, but it is used in certain medical fields such as ophthalmology and optics research. Here is a general definition:

Interferometry is a physical method that uses the interference of waves to measure the differences in phase between two or more waves. In other words, it's a technique that combines two or more light waves to create an interference pattern, which can then be analyzed to extract information about the properties of the light waves, such as their wavelength, amplitude, and phase.

In ophthalmology, interferometry is used in devices like wavefront sensors to measure the aberrations in the eye's optical system. By analyzing the interference pattern created by the light passing through the eye, these devices can provide detailed information about the shape and curvature of the cornea and lens, helping doctors to diagnose and treat various vision disorders.

In optics research, interferometry is used to study the properties of light waves and materials that interact with them. By analyzing the interference patterns created by light passing through different materials or devices, researchers can gain insights into their optical properties, such as their refractive index, thickness, and surface roughness.

Retinal diseases refer to a group of conditions that affect the retina, which is the light-sensitive tissue located at the back of the eye. The retina is responsible for converting light into electrical signals that are sent to the brain and interpreted as visual images. Retinal diseases can cause vision loss or even blindness, depending on their severity and location in the retina.

Some common retinal diseases include:

1. Age-related macular degeneration (AMD): A progressive disease that affects the central part of the retina called the macula, causing blurred or distorted vision.
2. Diabetic retinopathy: A complication of diabetes that can damage the blood vessels in the retina, leading to vision loss.
3. Retinal detachment: A serious condition where the retina becomes separated from its underlying tissue, requiring immediate medical attention.
4. Macular edema: Swelling or thickening of the macula due to fluid accumulation, which can cause blurred vision.
5. Retinitis pigmentosa: A group of inherited eye disorders that affect the retina's ability to respond to light, causing progressive vision loss.
6. Macular hole: A small break in the macula that can cause distorted or blurry vision.
7. Retinal vein occlusion: Blockage of the retinal veins that can lead to bleeding, swelling, and potential vision loss.

Treatment for retinal diseases varies depending on the specific condition and its severity. Some treatments include medication, laser therapy, surgery, or a combination of these options. Regular eye exams are essential for early detection and treatment of retinal diseases.

Optic nerve diseases refer to a group of conditions that affect the optic nerve, which transmits visual information from the eye to the brain. These diseases can cause various symptoms such as vision loss, decreased visual acuity, changes in color vision, and visual field defects. Examples of optic nerve diseases include optic neuritis (inflammation of the optic nerve), glaucoma (damage to the optic nerve due to high eye pressure), optic nerve damage from trauma or injury, ischemic optic neuropathy (lack of blood flow to the optic nerve), and optic nerve tumors. Treatment for optic nerve diseases varies depending on the specific condition and may include medications, surgery, or lifestyle changes.

I'm sorry for any confusion, but Fourier Analysis is not a medical term. It is a mathematical concept used in various scientific fields, including physics, engineering, and signal processing.

Fourier Analysis is a method to decompose functions into sinusoidal components (sines and cosines) of different frequencies. This allows for the representation of a function or a signal as a sum of these frequency components. It's particularly useful in analyzing periodic functions, understanding signals, and solving partial differential equations.

If you have any medical terms you would like me to define, please let me know!

Ophthalmoscopy is a medical examination technique used by healthcare professionals to observe the interior structures of the eye, including the retina, optic disc, and vitreous humor. This procedure typically involves using an ophthalmoscope, a handheld device that consists of a light and magnifying lenses. The healthcare provider looks through the ophthalmoscope and directly observes the internal structures of the eye by illuminating them.

There are several types of ophthalmoscopy, including direct ophthalmoscopy, indirect ophthalmoscopy, and slit-lamp biomicroscopy. Each type has its own advantages and disadvantages, and they may be used in different situations depending on the specific clinical situation and the information needed.

Ophthalmoscopy is an important diagnostic tool for detecting and monitoring a wide range of eye conditions, including diabetic retinopathy, glaucoma, age-related macular degeneration, and other retinal disorders. It can also provide valuable information about the overall health of the individual, as changes in the appearance of the retina or optic nerve may indicate the presence of systemic diseases such as hypertension or diabetes.

Optical phenomena refer to the various observable patterns and effects that occur due to the interaction of light with the environment or with structures in our eye. These can include natural phenomena such as rainbows, mirages, and halos around the sun or moon, as well as visual artifacts created by the eye itself, such as afterimages, floaters, and flashes of light. Some optical phenomena are caused by the refraction, reflection, or interference of light waves, while others may result from abnormalities in the eye's structure or function. Understanding these phenomena can provide insight into the properties of light and the functioning of the visual system.

The fovea centralis, also known as the macula lutea, is a small pit or depression located in the center of the retina, an light-sensitive tissue at the back of the eye. It is responsible for sharp, detailed vision (central vision) and color perception. The fovea contains only cones, the photoreceptor cells that are responsible for color vision and high visual acuity. It has a higher concentration of cones than any other area in the retina, allowing it to provide the greatest detail and color discrimination. The center of the fovea is called the foveola, which contains the highest density of cones and is avascular, meaning it lacks blood vessels to avoid interfering with the light passing through to the photoreceptor cells.

Three-dimensional (3D) imaging in medicine refers to the use of technologies and techniques that generate a 3D representation of internal body structures, organs, or tissues. This is achieved by acquiring and processing data from various imaging modalities such as X-ray computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, or confocal microscopy. The resulting 3D images offer a more detailed visualization of the anatomy and pathology compared to traditional 2D imaging techniques, allowing for improved diagnostic accuracy, surgical planning, and minimally invasive interventions.

In 3D imaging, specialized software is used to reconstruct the acquired data into a volumetric model, which can be manipulated and viewed from different angles and perspectives. This enables healthcare professionals to better understand complex anatomical relationships, detect abnormalities, assess disease progression, and monitor treatment response. Common applications of 3D imaging include neuroimaging, orthopedic surgery planning, cancer staging, dental and maxillofacial reconstruction, and interventional radiology procedures.

The anterior eye segment refers to the front portion of the eye, which includes the cornea, iris, ciliary body, and lens. The cornea is the clear, dome-shaped surface at the front of the eye that refracts light entering the eye and provides protection. The iris is the colored part of the eye that controls the amount of light reaching the retina by adjusting the size of the pupil. The ciliary body is a muscle that changes the shape of the lens to focus on objects at different distances. The lens is a transparent structure located behind the iris that further refracts light to provide a clear image. Together, these structures work to focus light onto the retina and enable vision.

Reproducibility of results in a medical context refers to the ability to obtain consistent and comparable findings when a particular experiment or study is repeated, either by the same researcher or by different researchers, following the same experimental protocol. It is an essential principle in scientific research that helps to ensure the validity and reliability of research findings.

In medical research, reproducibility of results is crucial for establishing the effectiveness and safety of new treatments, interventions, or diagnostic tools. It involves conducting well-designed studies with adequate sample sizes, appropriate statistical analyses, and transparent reporting of methods and findings to allow other researchers to replicate the study and confirm or refute the results.

The lack of reproducibility in medical research has become a significant concern in recent years, as several high-profile studies have failed to produce consistent findings when replicated by other researchers. This has led to increased scrutiny of research practices and a call for greater transparency, rigor, and standardization in the conduct and reporting of medical research.

"Fundus Oculi" is a medical term that refers to the back part of the interior of the eye, including the optic disc, macula, fovea, retinal vasculature, and peripheral retina. It is the area where light is focused and then transmitted to the brain via the optic nerve, forming visual images. Examinations of the fundus oculi are crucial for detecting various eye conditions such as diabetic retinopathy, macular degeneration, glaucoma, and other retinal diseases. The examination is typically performed using an ophthalmoscope or a specialized camera called a retinal camera.

Glaucoma is a group of eye conditions that damage the optic nerve, often caused by an abnormally high pressure in the eye (intraocular pressure). This damage can lead to permanent vision loss or even blindness if left untreated. The most common type is open-angle glaucoma, which has no warning signs and progresses slowly. Angle-closure glaucoma, on the other hand, can cause sudden eye pain, redness, nausea, and vomiting, as well as rapid vision loss. Other less common types of glaucoma also exist. While there is no cure for glaucoma, early detection and treatment can help slow or prevent further vision loss.

Positron-Emission Tomography (PET) is a type of nuclear medicine imaging that uses small amounts of radioactive material, called a radiotracer, to produce detailed, three-dimensional images. This technique measures metabolic activity within the body, such as sugar metabolism, to help distinguish between healthy and diseased tissue, identify cancerous cells, or examine the function of organs.

During a PET scan, the patient is injected with a radiotracer, typically a sugar-based compound labeled with a positron-emitting radioisotope, such as fluorine-18 (^18^F). The radiotracer accumulates in cells that are metabolically active, like cancer cells. As the radiotracer decays, it emits positrons, which then collide with electrons in nearby tissue, producing gamma rays. A special camera, called a PET scanner, detects these gamma rays and uses this information to create detailed images of the body's internal structures and processes.

PET is often used in conjunction with computed tomography (CT) or magnetic resonance imaging (MRI) to provide both functional and anatomical information, allowing for more accurate diagnosis and treatment planning. Common applications include detecting cancer recurrence, staging and monitoring cancer, evaluating heart function, and assessing brain function in conditions like dementia and epilepsy.

The choroid is a layer of the eye that contains blood vessels that supply oxygen and nutrients to the outer layers of the retina. It lies between the sclera (the white, protective coat of the eye) and the retina (the light-sensitive tissue at the back of the eye). The choroid is essential for maintaining the health and function of the retina, particularly the photoreceptor cells that detect light and transmit visual signals to the brain. Damage to the choroid can lead to vision loss or impairment.

A retinal perforation is a full-thickness break or hole in the retina, which is the light-sensitive tissue that lines the inner surface of the eye. This condition can lead to a serious complication called retinal detachment, where the retina separates from the underlying tissue, potentially resulting in vision loss if not promptly treated. Retinal perforations may be caused by trauma, certain eye conditions, or invasive eye procedures. Immediate medical attention is required for retinal perforations to prevent further damage and preserve vision.

A visual field test is a method used to measure an individual's entire scope of vision, which includes what can be seen straight ahead and in peripheral (or side) vision. During the test, the person being tested is asked to focus on a central point while gradually identifying the appearance of objects moving into their peripheral vision. The visual field test helps detect blind spots (scotomas) or gaps in the visual field, which can be caused by various conditions such as glaucoma, brain injury, optic nerve damage, or retinal disorders. It's an essential tool for diagnosing and monitoring eye-related diseases and conditions.

Gonioscopy is a diagnostic procedure in ophthalmology used to examine the anterior chamber angle, which is the area where the iris and cornea meet. This examination helps to evaluate the drainage pathways of the eye for conditions such as glaucoma. A special contact lens called a goniolens is placed on the cornea during the procedure to allow the healthcare provider to visualize the angle using a biomicroscope. The lens may be coupled with a mirrored or prismatic surface to enhance the view of the angle. Gonioscopy can help detect conditions like narrow angles, closed angles, neovascularization, and other abnormalities that might contribute to glaucoma development or progression.

An epiretinal membrane, also known as a macular pucker or cellophane maculopathy, is a thin and transparent layer of tissue that forms over the macula (the central part of the retina responsible for sharp, detailed vision) in the eye. This membrane can contract and wrinkle the macula, distorting central vision.

Epiretinal membranes are typically caused by the migration and proliferation of glial cells or other cell types onto the surface of the retina following retinal injury, inflammation, or aging. In some cases, they may be associated with other eye conditions such as diabetic retinopathy, retinal vein occlusion, or age-related macular degeneration.

Mild epiretinal membranes may not require treatment, but if the distortion of vision is significant, a vitrectomy surgery may be recommended to remove the membrane and improve visual acuity.

Cross-sectional anatomy refers to the study and visualization of the internal structures of the body as if they were cut along a plane, creating a two-dimensional image. This method allows for a detailed examination of the relationships between various organs, tissues, and structures that may not be as easily appreciated through traditional observation or examination.

In cross-sectional anatomy, different imaging techniques such as computed tomography (CT) scans, magnetic resonance imaging (MRI), and ultrasound are used to create detailed images of the body's internal structures at various depths and planes. These images can help medical professionals diagnose conditions, plan treatments, and assess the effectiveness of interventions.

Cross-sectional anatomy is an important tool in modern medicine, as it provides a more comprehensive understanding of the human body than traditional gross anatomy alone. By allowing for a detailed examination of the internal structures of the body, cross-sectional anatomy can help medical professionals make more informed decisions about patient care.

Equipment design, in the medical context, refers to the process of creating and developing medical equipment and devices, such as surgical instruments, diagnostic machines, or assistive technologies. This process involves several stages, including:

1. Identifying user needs and requirements
2. Concept development and brainstorming
3. Prototyping and testing
4. Design for manufacturing and assembly
5. Safety and regulatory compliance
6. Verification and validation
7. Training and support

The goal of equipment design is to create safe, effective, and efficient medical devices that meet the needs of healthcare providers and patients while complying with relevant regulations and standards. The design process typically involves a multidisciplinary team of engineers, clinicians, designers, and researchers who work together to develop innovative solutions that improve patient care and outcomes.

Visual fields refer to the total area in which objects can be seen while keeping the eyes focused on a central point. It is the entire area that can be observed using peripheral (side) vision while the eye gazes at a fixed point. A visual field test is used to detect blind spots or gaps (scotomas) in a person's vision, which could indicate various medical conditions such as glaucoma, retinal damage, optic nerve disease, brain tumors, or strokes. The test measures both the central and peripheral vision and maps the entire area that can be seen when focusing on a single point.

The retinal photoreceptor cells, namely rods and cones, are specialized neurons in the retina responsible for converting light into electrical signals that can be processed by the brain. The outer segment of a retinal photoreceptor cell is the portion of the cell where phototransduction primarily occurs. It contains stacks of disc-like structures filled with the visual pigment rhodopsin, which absorbs light and initiates the conversion process.

The outer segment is continuously renewed through a process called shedding and phagocytosis, in which the oldest discs at the base of the outer segment are shed, engulfed by the adjacent retinal pigment epithelium (RPE) cells, and degraded. This turnover helps maintain the sensitivity and functionality of the photoreceptor cells.

In summary, the retinal photoreceptor cell outer segment is a highly specialized compartment where light absorption and initial signal transduction occur in rods and cones, supported by continuous renewal through shedding and phagocytosis.

Corneal pachymetry is a medical measurement of the thickness of the cornea, which is the clear, dome-shaped surface at the front of the eye. This measurement is typically taken using a specialized instrument called a pachymeter. The procedure is quick, painless, and non-invasive.

Corneal pachymetry is an essential test in optometry and ophthalmology for various reasons. For instance, it helps assess the overall health of the cornea, identify potential abnormalities or diseases, and determine the correct intraocular lens power during cataract surgery. Additionally, corneal thickness is a crucial factor in determining a person's risk for developing glaucoma and monitoring the progression of the disease.

In some cases, such as with contact lens fitting, corneal pachymetry can help ensure proper fit and minimize potential complications. Overall, corneal pachymetry is an essential diagnostic tool in eye care that provides valuable information for maintaining eye health and ensuring appropriate treatment.

The retinal pigment epithelium (RPE) is a single layer of cells located between the photoreceptor cells of the retina and the choroid, which is a part of the eye containing blood vessels. The RPE plays a crucial role in maintaining the health and function of the photoreceptors by providing them with nutrients, removing waste products, and helping to regulate the light-sensitive visual pigments within the photoreceptors.

The RPE cells contain pigment granules that absorb excess light to prevent scattering within the eye and improve visual acuity. They also help to form the blood-retina barrier, which restricts the movement of certain molecules between the retina and the choroid, providing an important protective function for the retina.

Damage to the RPE can lead to a variety of eye conditions, including age-related macular degeneration (AMD), which is a leading cause of vision loss in older adults.

The inner segment of a retinal photoreceptor cell, also known as the inner segment of a rod or cone cell, is the portion of the cell that contains the majority of its metabolic and energy-generating components. It is responsible for providing the energy needed for the outer segment, which is the part of the cell that contains the visual pigments and is responsible for phototransduction, or the conversion of light into electrical signals.

The inner segment is divided into two main parts: the ellipsoid and the myoid. The ellipsoid contains a high concentration of mitochondria, which provide energy to the cell through the process of oxidative phosphorylation. The myoid contains the endoplasmic reticulum and the Golgi apparatus, which are involved in protein synthesis and transport.

Damage to the inner segment of the retinal photoreceptor cells can lead to vision loss or impairment, as it can affect the ability of the outer segment to function properly and transmit visual signals to the brain.

Emission computed tomography (ECT) is a type of tomographic imaging technique in which an emission signal from within the body is detected to create cross-sectional images of that signal's distribution. In Emission-Computed Tomography (ECT), a radionuclide is introduced into the body, usually through injection, inhalation or ingestion. The radionuclide emits gamma rays that are then detected by external gamma cameras.

The data collected from these cameras is then used to create cross-sectional images of the distribution of the radiopharmaceutical within the body. This allows for the identification and quantification of functional information about specific organs or systems within the body, such as blood flow, metabolic activity, or receptor density.

One common type of Emission-Computed Tomography is Single Photon Emission Computed Tomography (SPECT), which uses a single gamma camera that rotates around the patient to collect data from multiple angles. Another type is Positron Emission Tomography (PET), which uses positron-emitting radionuclides and detects the coincident gamma rays emitted by the annihilation of positrons and electrons.

Overall, ECT is a valuable tool in medical imaging for diagnosing and monitoring various diseases, including cancer, heart disease, and neurological disorders.

Optical Tomography (OT) is a non-invasive imaging technique that uses light to visualize and measure the optical properties of tissue, such as absorption and scattering coefficients. This modality can be used to produce cross-sectional or three-dimensional images of internal structures, providing functional information about tissue physiology. It has applications in various fields including biomedical research, dermatology, and oncology for the detection and monitoring of diseases. There are different types of optical tomography, such as diffuse optical tomography (DOT) and near-infrared spectroscopy (NIRS), which differ in their light sources, detection schemes, and data analysis methods.

Neointima is a term used in pathology and refers to the layer of tissue that forms inside a blood vessel as part of the healing process after an injury, such as angioplasty or stenting. This new tissue is composed mainly of smooth muscle cells and extracellular matrix and can grow inward, potentially causing restenosis (re-narrowing) of the vessel lumen.

In simpler terms, Neointima is a type of scar tissue that forms inside blood vessels as part of the healing process after an injury, but its growth can sometimes cause problems by narrowing the vessel and restricting blood flow.

Acoustic microscopy is a non-invasive imaging technique that uses sound waves to visualize and analyze the structure and properties of various materials, including biological samples. In the context of medical diagnostics and research, acoustic microscopy can be used to examine tissues, cells, and cellular components with high resolution, providing valuable information about their mechanical and physical properties.

In acoustic microscopy, high-frequency sound waves are focused onto a sample using a transducer. The interaction between the sound waves and the sample generates echoes, which contain information about the sample's internal structure and properties. These echoes are then recorded and processed to create an image of the sample.

Acoustic microscopy offers several advantages over other imaging techniques, such as optical microscopy or electron microscopy. For example, it does not require staining or labeling of samples, which can be time-consuming and potentially damaging. Additionally, acoustic microscopy can provide high-resolution images of samples in their native state, allowing researchers to study the effects of various treatments or interventions on living cells and tissues.

In summary, acoustic microscopy is a non-invasive imaging technique that uses sound waves to visualize and analyze the structure and properties of biological samples with high resolution, providing valuable information for medical diagnostics and research.

Image enhancement in the medical context refers to the process of improving the quality and clarity of medical images, such as X-rays, CT scans, MRI scans, or ultrasound images, to aid in the diagnosis and treatment of medical conditions. Image enhancement techniques may include adjusting contrast, brightness, or sharpness; removing noise or artifacts; or applying specialized algorithms to highlight specific features or structures within the image.

The goal of image enhancement is to provide clinicians with more accurate and detailed information about a patient's anatomy or physiology, which can help inform medical decision-making and improve patient outcomes.

An ophthalmoscope is a medical device used by healthcare professionals to examine the interior structures of the eye, including the retina, optic disc, and vitreous humor. It consists of a handle with a battery-powered light source and a head that contains lenses for focusing. When placed in contact with the patient's dilated pupil, the ophthalmoscope allows the examiner to visualize the internal structures of the eye and assess their health. Ophthalmoscopes are commonly used in routine eye examinations, as well as in the diagnosis and management of various eye conditions and diseases.

The choroid is a part of the eye located between the retina and the sclera, which contains a large number of blood vessels that supply oxygen and nutrients to the outer layers of the retina. Choroid diseases refer to various medical conditions that affect the health and function of the choroid. Here are some examples:

1. Choroidal neovascularization (CNV): This is a condition where new blood vessels grow from the choroid into the retina, leading to fluid accumulation, bleeding, and scarring. CNV can cause vision loss and is often associated with age-related macular degeneration, myopia, and inflammatory eye diseases.
2. Chorioretinitis: This is an infection or inflammation of the choroid and retina, which can be caused by various microorganisms such as bacteria, viruses, fungi, or parasites. Symptoms may include blurred vision, floaters, light sensitivity, and eye pain.
3. Choroidal hemorrhage: This is a rare but serious condition where there is bleeding into the choroid, often caused by trauma, high blood pressure, or blood clotting disorders. It can lead to sudden vision loss and requires urgent medical attention.
4. Choroideremia: This is a genetic disorder that affects the choroid, retina, and optic nerve, leading to progressive vision loss. It is caused by mutations in the CHM gene and primarily affects males.
5. Central serous retinopathy (CSR): This is a condition where fluid accumulates under the retina, often in the macula, causing distortion or blurring of vision. While the exact cause is unknown, CSR is thought to be related to stress, steroid use, and other factors that affect the choroid's ability to regulate fluid.
6. Polypoidal choroidal vasculopathy (PCV): This is a condition where abnormal blood vessels form in the choroid, leading to serous or hemorrhagic detachment of the retina. PCV is often associated with age-related macular degeneration and can cause vision loss if left untreated.

These are just a few examples of choroidal disorders that can affect vision. If you experience any sudden changes in your vision, it's important to seek medical attention promptly.

Macular degeneration, also known as age-related macular degeneration (AMD), is a medical condition that affects the central part of the retina, called the macula. The macula is responsible for sharp, detailed vision, which is necessary for activities such as reading, driving, and recognizing faces.

In AMD, there is a breakdown or deterioration of the macula, leading to gradual loss of central vision. There are two main types of AMD: dry (atrophic) and wet (exudative). Dry AMD is more common and progresses more slowly, while wet AMD is less common but can cause rapid and severe vision loss if left untreated.

The exact causes of AMD are not fully understood, but risk factors include age, smoking, family history, high blood pressure, obesity, and exposure to sunlight. While there is no cure for AMD, treatments such as vitamin supplements, laser therapy, and medication injections can help slow its progression and reduce the risk of vision loss.

Intraocular pressure (IOP) is the fluid pressure within the eye, specifically within the anterior chamber, which is the space between the cornea and the iris. It is measured in millimeters of mercury (mmHg). The aqueous humor, a clear fluid that fills the anterior chamber, is constantly produced and drained, maintaining a balance that determines the IOP. Normal IOP ranges from 10-21 mmHg, with average values around 15-16 mmHg. Elevated IOP is a key risk factor for glaucoma, a group of eye conditions that can lead to optic nerve damage and vision loss if not treated promptly and effectively. Regular monitoring of IOP is essential in diagnosing and managing glaucoma and other ocular health issues.

Vitreous detachment, also known as posterior vitreous detachment (PVD), is a common age-related eye condition characterized by the separation of the vitreous gel from the retina. The vitreous is a clear, gel-like substance that fills the space between the lens and the retina in the eye. As we age, the vitreous may change in consistency, becoming more liquefied, leading to the formation of pockets of liquid within the gel.

In vitreous detachment, the posterior part of the vitreous closest to the retina begins to pull away from the retinal surface due to the shrinkage and liquefaction of the vitreous gel. This separation can cause symptoms such as floaters (spots or strands in the field of vision), flashes of light, or a decrease in vision sharpness. While vitreous detachment is typically not a serious condition on its own, it can sometimes lead to complications like retinal tears or retinal detachment, which require immediate medical attention.

Spiral Computed Tomography (CT), also known as Helical CT, is a type of computed tomography scan in which the X-ray tube and detector rotate around the patient in a spiral path, capturing data as the table moves the patient through the scanner. This continuous spiral motion allows for faster and more detailed volumetric imaging of internal organs and structures, reducing the need for multiple slices and providing improved image reconstruction. It is commonly used to diagnose and monitor various medical conditions, including cancer, heart disease, and trauma injuries.

I'm sorry for any confusion, but "Optics and Photonics" is a broad field that encompasses various scientific and engineering disciplines. It doesn't have a specific medical definition, as it's not a term typically used in a medical context.

However, I can provide a general definition:

Optics is the study of light and its interactions with matter. This includes how light is produced, controlled, transmitted, and detected. It involves phenomena such as reflection, refraction, diffraction, and interference.

Photonics, on the other hand, is a branch of optics that deals with the generation, detection, and manipulation of individual photons, the basic units of light. Photonics is often applied to technologies such as lasers, fiber optics, and optical communications.

In a medical context, these fields might be used in various diagnostic and therapeutic applications, such as endoscopes, ophthalmic devices, laser surgery, and imaging technologies like MRI and CT scans. But the terms "Optics" and "Photonics" themselves are not medical conditions or treatments.

Equipment Failure Analysis is a process of identifying the cause of failure in medical equipment or devices. This involves a systematic examination and evaluation of the equipment, its components, and operational history to determine why it failed. The analysis may include physical inspection, chemical testing, and review of maintenance records, as well as assessment of design, manufacturing, and usage factors that may have contributed to the failure.

The goal of Equipment Failure Analysis is to identify the root cause of the failure, so that corrective actions can be taken to prevent similar failures in the future. This is important in medical settings to ensure patient safety and maintain the reliability and effectiveness of medical equipment.

A retinoscope is an ophthalmic instrument used by eye care professionals to perform a retinoscopy examination, which is a subjective test used to estimate the refractive error and determine the prescription for eyeglasses or contact lenses. The retinoscope emits a beam of light that is shined onto the patient's retina, and the practitioner observes the reflection of the light (called the "reflex") as it passes through the pupil.

By adjusting the orientation and focus of the retinoscope's light, the practitioner can observe how the reflex changes, which provides information about the patient's refractive error. The retinoscope is an essential tool in eye examinations, particularly for children who may not be able to provide reliable answers to subjective questions about their vision.

Sensitivity and specificity are statistical measures used to describe the performance of a diagnostic test or screening tool in identifying true positive and true negative results.

* Sensitivity refers to the proportion of people who have a particular condition (true positives) who are correctly identified by the test. It is also known as the "true positive rate" or "recall." A highly sensitive test will identify most or all of the people with the condition, but may also produce more false positives.
* Specificity refers to the proportion of people who do not have a particular condition (true negatives) who are correctly identified by the test. It is also known as the "true negative rate." A highly specific test will identify most or all of the people without the condition, but may also produce more false negatives.

In medical testing, both sensitivity and specificity are important considerations when evaluating a diagnostic test. High sensitivity is desirable for screening tests that aim to identify as many cases of a condition as possible, while high specificity is desirable for confirmatory tests that aim to rule out the condition in people who do not have it.

It's worth noting that sensitivity and specificity are often influenced by factors such as the prevalence of the condition in the population being tested, the threshold used to define a positive result, and the reliability and validity of the test itself. Therefore, it's important to consider these factors when interpreting the results of a diagnostic test.

Axial length, in the context of the eye, refers to the measurement of the distance between the front and back portions of the eye, specifically from the cornea (the clear front "window" of the eye) to the retina (the light-sensitive tissue at the back of the eye). This measurement is typically expressed in millimeters (mm).

The axial length of the eye is an important factor in determining the overall refractive power of the eye and can play a role in the development of various eye conditions, such as myopia (nearsightedness) or hyperopia (farsightedness). Changes in axial length, particularly elongation, are often associated with an increased risk of developing myopia. Regular monitoring of axial length can help eye care professionals track changes in the eye and manage these conditions more effectively.

Retinal detachment is a serious eye condition that occurs when the retina, a thin layer of tissue at the back of the eye responsible for processing light and sending visual signals to the brain, pulls away from its normal position. This can lead to significant vision loss or even blindness if not promptly treated. Retinal detachment can be caused by various factors such as aging, trauma, eye disease, or an inflammatory condition. Symptoms of retinal detachment may include sudden flashes of light, floaters, a shadow in the peripheral vision, or a curtain-like covering over part of the visual field. Immediate medical attention is necessary to prevent further damage and preserve vision.

Subretinal fluid (SRF) refers to the abnormal accumulation of fluid between the neurosensory retina and the pigment epithelium of the eye. This can occur due to various conditions such as age-related macular degeneration, central serous chorioretinopathy, or retinal detachment. The presence of subretinal fluid can distort vision and may require medical intervention depending on the underlying cause and severity of the condition.

Degenerative Myopia is a progressive form of nearsightedness, characterized by excessive elongation of the eyeball, which results in a steep curvature of the cornea and an overly long axial length. This condition causes light to focus in front of the retina instead of directly on it, resulting in blurred distance vision.

In degenerative myopia, this elongation continues throughout adulthood and is often associated with various complications such as thinning of the retinal tissue, stretching of the layers beneath the retina, and abnormal blood vessel growth. These changes can lead to a higher risk of developing retinal detachment, macular holes, glaucoma, and cataracts.

Degenerative myopia is considered a more severe form of myopia than the common or simple myopia, which usually stabilizes in the teenage years. It is also sometimes referred to as pathological myopia or malignant myopia. Regular eye examinations are essential for individuals with degenerative myopia to monitor and manage any potential complications.

Computer-assisted image processing is a medical term that refers to the use of computer systems and specialized software to improve, analyze, and interpret medical images obtained through various imaging techniques such as X-ray, CT (computed tomography), MRI (magnetic resonance imaging), ultrasound, and others.

The process typically involves several steps, including image acquisition, enhancement, segmentation, restoration, and analysis. Image processing algorithms can be used to enhance the quality of medical images by adjusting contrast, brightness, and sharpness, as well as removing noise and artifacts that may interfere with accurate diagnosis. Segmentation techniques can be used to isolate specific regions or structures of interest within an image, allowing for more detailed analysis.

Computer-assisted image processing has numerous applications in medical imaging, including detection and characterization of lesions, tumors, and other abnormalities; assessment of organ function and morphology; and guidance of interventional procedures such as biopsies and surgeries. By automating and standardizing image analysis tasks, computer-assisted image processing can help to improve diagnostic accuracy, efficiency, and consistency, while reducing the potential for human error.

Refractometry is a medical laboratory technique used to measure the refractive index of a substance, typically a liquid. The refractive index is the ratio of the speed of light in a vacuum to its speed in the substance being measured. In a clinical setting, refractometry is often used to determine the concentration of total solids in a fluid, such as urine or serum, by measuring the angle at which light passes through the sample. This information can be useful in the diagnosis and monitoring of various medical conditions, including dehydration, kidney disease, and diabetes. Refractometry is also used in the field of optometry to measure the refractive error of the eye, or the amount and type of correction needed to provide clear vision.

Diabetic retinopathy is a diabetes complication that affects the eyes. It's caused by damage to the blood vessels of the light-sensitive tissue at the back of the eye (retina).

At first, diabetic retinopathy may cause no symptoms or only mild vision problems. Eventually, it can cause blindness. The condition usually affects both eyes.

There are two main stages of diabetic retinopathy:

1. Early diabetic retinopathy. This is when the blood vessels in the eye start to leak fluid or bleed. You might not notice any changes in your vision at this stage, but it's still important to get treatment because it can prevent the condition from getting worse.
2. Advanced diabetic retinopathy. This is when new, abnormal blood vessels grow on the surface of the retina. These vessels can leak fluid and cause severe vision problems, including blindness.

Diabetic retinopathy can be treated with laser surgery, injections of medication into the eye, or a vitrectomy (a surgical procedure to remove the gel-like substance that fills the center of the eye). It's important to get regular eye exams to detect diabetic retinopathy early and get treatment before it causes serious vision problems.

Retinoschisis is a medical term that refers to a specific eye condition where there is a separation (schisis) of the retinal layers, particularly the neurosensory retina. This condition often affects the peripheral retina and can be classified as congenital or acquired. Congenital retinoschisis is usually present at birth or develops during early childhood, while acquired retinoschisis occurs later in life due to various reasons such as trauma, inflammation, or degenerative changes.

In retinoschisis, the inner layers of the retina split apart, creating a cavity filled with fluid. This separation can lead to visual symptoms like blurred vision, shadows, or blind spots in the affected area of the visual field. However, it is important to note that many cases of retinoschisis do not cause significant visual impairment and may only require monitoring by an eye care professional.

Retinoschisis can be diagnosed through a comprehensive eye examination, including a dilated fundus exam, which allows the eye care professional to examine the retina thoroughly. In some cases, additional diagnostic tests like optical coherence tomography (OCT) or fluorescein angiography may be used to confirm the diagnosis and assess the extent of the condition.

Treatment for retinoschisis depends on the severity and location of the separation. Mild cases may not require any treatment, while more severe cases may need surgical intervention to prevent complications such as retinal detachment or bleeding in the eye. Regular follow-up appointments with an eye care professional are essential to monitor the condition and ensure appropriate management.

Electroretinography (ERG) is a medical test used to evaluate the functioning of the retina, which is the light-sensitive tissue located at the back of the eye. The test measures the electrical responses of the retina to light stimulation.

During the procedure, a special contact lens or electrode is placed on the surface of the eye to record the electrical activity generated by the retina's light-sensitive cells (rods and cones) and other cells in the retina. The test typically involves presenting different levels of flashes of light to the eye while the electrical responses are recorded.

The resulting ERG waveform provides information about the overall health and function of the retina, including the condition of the photoreceptors, the integrity of the inner retinal layers, and the health of the retinal ganglion cells. This test is often used to diagnose and monitor various retinal disorders, such as retinitis pigmentosa, macular degeneration, and diabetic retinopathy.

Optic disk drusen are small, calcified deposits that form within the optic nerve head, also known as the optic disc. They are made up of protein and calcium salts and can vary in size and number. These deposits can be seen on ophthalmic examination using an instrument called an ophthalmoscope.

Optic disk drusen are typically asymptomatic and are often discovered during routine eye examinations. However, in some cases, they may cause visual disturbances or even vision loss if they compress the optic nerve fibers. They can also increase the risk of developing other eye conditions such as glaucoma.

Optic disk drusen are more commonly found in individuals with a family history of the condition and tend to occur in younger people, typically before the age of 40. While there is no cure for optic disk drusen, regular eye examinations can help monitor any changes in the condition and manage any associated visual symptoms or complications.

I'm sorry for any confusion, but "photography" is not a term typically used in medical definitions. Photography refers to the art, application, or process of creating images by recording light or other electromagnetic radiation, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film.

If you're looking for a medical term related to imaging, there are several terms that might be relevant, such as:

1. Radiography: This is a technique using X-rays to visualize the internal structures of the body.
2. Ultrasonography: Also known as ultrasound, this is a diagnostic imaging technique using high-frequency sound waves to create images of the inside of the body.
3. Computed Tomography (CT): A type of imaging that uses X-rays to create detailed cross-sectional images of the body.
4. Magnetic Resonance Imaging (MRI): A type of imaging that uses magnetic fields and radio waves to create detailed images of the organs and tissues within the body.
5. Nuclear Medicine: This is a branch of medical imaging that uses small amounts of radioactive material to diagnose and treat diseases.

If you have any questions related to medical definitions or topics, feel free to ask!

The anterior chamber is the front portion of the eye, located between the cornea (the clear front "window" of the eye) and the iris (the colored part of the eye). It is filled with a clear fluid called aqueous humor that provides nutrients to the structures inside the eye and helps maintain its shape. The anterior chamber plays an important role in maintaining the overall health and function of the eye.

The cornea is the clear, dome-shaped surface at the front of the eye. It plays a crucial role in focusing vision. The cornea protects the eye from harmful particles and microorganisms, and it also serves as a barrier against UV light. Its transparency allows light to pass through and get focused onto the retina. The cornea does not contain blood vessels, so it relies on tears and the fluid inside the eye (aqueous humor) for nutrition and oxygen. Any damage or disease that affects its clarity and shape can significantly impact vision and potentially lead to blindness if left untreated.

Open-angle glaucoma is a chronic, progressive type of glaucoma characterized by the gradual loss of optic nerve fibers and resulting in visual field defects. It is called "open-angle" because the angle where the iris meets the cornea (trabecular meshwork) appears to be normal and open on examination. The exact cause of this condition is not fully understood, but it is associated with increased resistance to the outflow of aqueous humor within the trabecular meshwork, leading to an increase in intraocular pressure (IOP). This elevated IOP can cause damage to the optic nerve and result in vision loss.

The onset of open-angle glaucoma is often asymptomatic, making regular comprehensive eye examinations crucial for early detection and management. Treatment typically involves lowering IOP using medications, laser therapy, or surgery to prevent further optic nerve damage and preserve vision.

An algorithm is not a medical term, but rather a concept from computer science and mathematics. In the context of medicine, algorithms are often used to describe step-by-step procedures for diagnosing or managing medical conditions. These procedures typically involve a series of rules or decision points that help healthcare professionals make informed decisions about patient care.

For example, an algorithm for diagnosing a particular type of heart disease might involve taking a patient's medical history, performing a physical exam, ordering certain diagnostic tests, and interpreting the results in a specific way. By following this algorithm, healthcare professionals can ensure that they are using a consistent and evidence-based approach to making a diagnosis.

Algorithms can also be used to guide treatment decisions. For instance, an algorithm for managing diabetes might involve setting target blood sugar levels, recommending certain medications or lifestyle changes based on the patient's individual needs, and monitoring the patient's response to treatment over time.

Overall, algorithms are valuable tools in medicine because they help standardize clinical decision-making and ensure that patients receive high-quality care based on the latest scientific evidence.

Retinal drusen are yellow-white, deposits of extracellular material that accumulate beneath the retina, most commonly in the macula. They are a common age-related finding and can also be seen in various other conditions such as inherited retinal diseases. Drusen can vary in size and number, and their presence is often associated with an increased risk of developing age-related macular degeneration (AMD), a leading cause of vision loss in older adults. However, not all individuals with drusen will develop AMD, and the significance of drusen depends on factors such as size, number, and location. It's important to monitor drusen and have regular eye examinations to assess any changes or progression that may indicate a higher risk for developing AMD.

Interventional ultrasonography is a medical procedure that involves the use of real-time ultrasound imaging to guide minimally invasive diagnostic and therapeutic interventions. This technique combines the advantages of ultrasound, such as its non-ionizing nature (no radiation exposure), relatively low cost, and portability, with the ability to perform precise and targeted procedures.

In interventional ultrasonography, a specialized physician called an interventional radiologist or an interventional sonographer uses high-frequency sound waves to create detailed images of internal organs and tissues. These images help guide the placement of needles, catheters, or other instruments used during the procedure. Common interventions include biopsies (tissue sampling), fluid drainage, tumor ablation, and targeted drug delivery.

The real-time visualization provided by ultrasonography allows for increased accuracy and safety during these procedures, minimizing complications and reducing recovery time compared to traditional surgical approaches. Additionally, interventional ultrasonography can be performed on an outpatient basis, further contributing to its appeal as a less invasive alternative in many clinical scenarios.

Choroidal neovascularization (CNV) is a medical term that refers to the growth of new, abnormal blood vessels in the choroid layer of the eye, which is located between the retina and the sclera. This condition typically occurs as a complication of age-related macular degeneration (AMD), although it can also be caused by other eye diseases or injuries.

In CNV, the new blood vessels that grow into the choroid layer are fragile and can leak fluid or blood, which can cause distortion or damage to the retina, leading to vision loss. Symptoms of CNV may include blurred or distorted vision, a blind spot in the center of the visual field, or changes in color perception.

Treatment for CNV typically involves medications that are designed to stop the growth of new blood vessels, such as anti-VEGF drugs, which target a protein called vascular endothelial growth factor (VEGF) that is involved in the development of new blood vessels. Laser surgery or photodynamic therapy may also be used in some cases to destroy the abnormal blood vessels and prevent further vision loss.

Prospective studies, also known as longitudinal studies, are a type of cohort study in which data is collected forward in time, following a group of individuals who share a common characteristic or exposure over a period of time. The researchers clearly define the study population and exposure of interest at the beginning of the study and follow up with the participants to determine the outcomes that develop over time. This type of study design allows for the investigation of causal relationships between exposures and outcomes, as well as the identification of risk factors and the estimation of disease incidence rates. Prospective studies are particularly useful in epidemiology and medical research when studying diseases with long latency periods or rare outcomes.

A vitrectomy is a surgical procedure that involves the removal of some or all of the vitreous humor, which is the clear gel-like substance filling the center of the eye. This surgery is often performed to treat various retinal disorders such as diabetic retinopathy, retinal detachment, macular hole, and vitreous hemorrhage.

During a vitrectomy, the ophthalmologist makes small incisions in the sclera (the white part of the eye) to access the vitreous cavity. The surgeon then uses specialized instruments to remove the cloudy or damaged vitreous and may also repair any damage to the retina or surrounding tissues. Afterward, a clear saline solution is injected into the eye to maintain its shape and help facilitate healing.

In some cases, a gas bubble or silicone oil may be placed in the eye after the vitrectomy to help hold the retina in place while it heals. These substances will gradually be absorbed or removed during follow-up appointments. The body naturally produces a new, clear vitreous to replace the removed material over time.

Vitrectomy is typically performed under local anesthesia and may require hospitalization or outpatient care depending on the individual case. Potential risks and complications include infection, bleeding, cataract formation, retinal detachment, and increased eye pressure. However, with proper care and follow-up, most patients experience improved vision after a successful vitrectomy procedure.

Multidetector computed tomography (MDCT) is a type of computed tomography (CT) scan that uses multiple rows of detectors to acquire several slices of images simultaneously, thereby reducing the total time required for the scan and improving the spatial resolution. This technology allows for faster scanning of moving organs, such as the heart, and provides high-resolution images with detailed information about various body structures, including bones, soft tissues, and blood vessels. MDCT has numerous applications in diagnostic imaging, interventional procedures, and cancer staging and treatment follow-up.

Retinal neurons are the specialized nerve cells located in the retina, which is the light-sensitive tissue that lines the inner surface of the eye. The retina converts incoming light into electrical signals, which are then transmitted to the brain and interpreted as visual images. There are several types of retinal neurons, including:

1. Photoreceptors (rods and cones): These are the primary sensory cells that convert light into electrical signals. Rods are responsible for low-light vision, while cones are responsible for color vision and fine detail.
2. Bipolar cells: These neurons receive input from photoreceptors and transmit signals to ganglion cells. They can be either ON or OFF bipolar cells, depending on whether they respond to an increase or decrease in light intensity.
3. Ganglion cells: These are the output neurons of the retina that send visual information to the brain via the optic nerve. There are several types of ganglion cells, including parasol, midget, and small bistratified cells, which have different functions in processing visual information.
4. Horizontal cells: These interneurons connect photoreceptors to each other and help regulate the sensitivity of the retina to light.
5. Amacrine cells: These interneurons connect bipolar cells to ganglion cells and play a role in modulating the signals that are transmitted to the brain.

Overall, retinal neurons work together to process visual information and transmit it to the brain for further analysis and interpretation.

An endoscope is a medical device used for examining the interior of a body cavity or organ. It consists of a long, thin, flexible (or rigid) tube with a light and a camera at one end. The other end is connected to a video monitor that displays the images captured by the camera. Endoscopes can be inserted through natural openings in the body, such as the mouth or anus, or through small incisions. They are used for diagnostic purposes, as well as for performing various medical procedures, including biopsies and surgeries. Different types of endoscopes include gastroscopes, colonoscopes, bronchoscopes, and arthroscopes, among others.

Photoreceptor cells in vertebrates are specialized types of neurons located in the retina of the eye that are responsible for converting light stimuli into electrical signals. These cells are primarily responsible for the initial process of vision and have two main types: rods and cones.

Rods are more numerous and are responsible for low-light vision or scotopic vision, enabling us to see in dimly lit conditions. They do not contribute to color vision but provide information about the shape and movement of objects.

Cones, on the other hand, are less numerous and are responsible for color vision and high-acuity vision or photopic vision. There are three types of cones, each sensitive to different wavelengths of light: short (S), medium (M), and long (L) wavelengths, which correspond to blue, green, and red, respectively. The combination of signals from these three types of cones allows us to perceive a wide range of colors.

Both rods and cones contain photopigments that consist of a protein called opsin and a light-sensitive chromophore called retinal. When light hits the photopigment, it triggers a series of chemical reactions that ultimately lead to the generation of an electrical signal that is transmitted to the brain via the optic nerve. This process enables us to see and perceive our visual world.

An intravitreal injection is a medical procedure in which medication is delivered directly into the vitreous cavity of the eye, which is the clear, gel-like substance that fills the space between the lens and the retina. This type of injection is typically used to treat various eye conditions such as age-related macular degeneration, diabetic retinopathy, retinal vein occlusion, and uveitis. The medication administered in intravitreal injections can help to reduce inflammation, inhibit the growth of new blood vessels, or prevent the formation of abnormal blood vessels in the eye.

Intravitreal injections are usually performed in an outpatient setting, and the procedure typically takes only a few minutes. Before the injection, the eye is numbed with anesthetic drops to minimize discomfort. The medication is then injected into the vitreous cavity using a small needle. After the injection, patients may experience some mild discomfort or a scratchy sensation in the eye, but this usually resolves within a few hours.

While intravitreal injections are generally safe, there are some potential risks and complications associated with the procedure, including infection, bleeding, retinal detachment, and increased intraocular pressure. Patients who undergo intravitreal injections should be closely monitored by their eye care provider to ensure that any complications are promptly identified and treated.

Medical Definition of Optical Fibers:

Optical fibers are thin, transparent strands of glass or plastic fiber that are designed to transmit light along their length. In the medical field, optical fibers are used in various applications such as illumination, imaging, and data transmission. For instance, they are used in flexible endoscopes to provide illumination and visualization inside the body during diagnostic or surgical procedures. They are also used in optical communication systems for transmitting information in the form of light signals within medical devices or between medical facilities. The use of optical fibers allows for minimally invasive procedures, improved image quality, and increased data transmission rates.

Scleral diseases refer to conditions that affect the sclera, which is the tough, white outer coating of the eye. The sclera helps to maintain the shape of the eye and provides protection for the internal structures. Scleral diseases can cause inflammation, degeneration, or thinning of the sclera, leading to potential vision loss or other complications. Some examples of scleral diseases include:

1. Scleritis: an inflammatory condition that causes pain, redness, and sensitivity in the affected area of the sclera. It can be associated with autoimmune disorders, infections, or trauma.
2. Episcleritis: a less severe form of inflammation that affects only the episclera, a thin layer of tissue overlying the sclera. Symptoms include redness and mild discomfort but typically no pain.
3. Pinguecula: a yellowish, raised deposit of protein and fat that forms on the conjunctiva, the clear membrane covering the sclera. While not a disease itself, a pinguecula can cause irritation or discomfort and may progress to a more severe condition called a pterygium.
4. Pterygium: a fleshy growth that extends from the conjunctiva onto the cornea, potentially obstructing vision. It is often associated with prolonged sun exposure and can be removed surgically if it becomes problematic.
5. Scleral thinning or melting: a rare but serious condition where the sclera degenerates or liquefies, leading to potential perforation of the eye. This can occur due to autoimmune disorders, infections, or as a complication of certain surgical procedures.
6. Ocular histoplasmosis syndrome (OHS): a condition caused by the Histoplasma capsulatum fungus, which can lead to scarring and vision loss if it involves the macula, the central part of the retina responsible for sharp, detailed vision.

It is essential to consult an ophthalmologist or eye care professional if you experience any symptoms related to scleral diseases to receive proper diagnosis and treatment.

Computer-assisted image interpretation is the use of computer algorithms and software to assist healthcare professionals in analyzing and interpreting medical images. These systems use various techniques such as pattern recognition, machine learning, and artificial intelligence to help identify and highlight abnormalities or patterns within imaging data, such as X-rays, CT scans, MRI, and ultrasound images. The goal is to increase the accuracy, consistency, and efficiency of image interpretation, while also reducing the potential for human error. It's important to note that these systems are intended to assist healthcare professionals in their decision making process and not to replace them.

The vitreous body, also known simply as the vitreous, is the clear, gel-like substance that fills the space between the lens and the retina in the eye. It is composed mainly of water, but also contains collagen fibers, hyaluronic acid, and other proteins. The vitreous helps to maintain the shape of the eye and provides a transparent medium for light to pass through to reach the retina. With age, the vitreous can become more liquefied and may eventually separate from the retina, leading to symptoms such as floaters or flashes of light.

Emission-Computed Tomography, Single-Photon (SPECT) is a type of nuclear medicine imaging procedure that generates detailed, three-dimensional images of the distribution of radioactive pharmaceuticals within the body. It uses gamma rays emitted by a radiopharmaceutical that is introduced into the patient's body, and a specialized gamma camera to detect these gamma rays and create tomographic images. The data obtained from the SPECT imaging can be used to diagnose various medical conditions, evaluate organ function, and guide treatment decisions. It is commonly used to image the heart, brain, and bones, among other organs and systems.

Angle-closure glaucoma is a type of glaucoma that is characterized by the sudden or gradually increasing pressure in the eye (intraocular pressure) due to the closure or narrowing of the angle between the iris and cornea. This angle is where the drainage system of the eye, called the trabecular meshwork, is located. When the angle becomes too narrow or closes completely, fluid cannot properly drain from the eye, leading to a buildup of pressure that can damage the optic nerve and cause permanent vision loss.

Angle-closure glaucoma can be either acute or chronic. Acute angle-closure glaucoma is a medical emergency that requires immediate treatment to prevent permanent vision loss. It is characterized by sudden symptoms such as severe eye pain, nausea and vomiting, blurred vision, halos around lights, and redness of the eye.

Chronic angle-closure glaucoma, on the other hand, develops more slowly over time and may not have any noticeable symptoms until significant damage has already occurred. It is important to diagnose and treat angle-closure glaucoma as early as possible to prevent vision loss. Treatment options include medications to lower eye pressure, laser treatment to create a new opening for fluid drainage, or surgery to improve the flow of fluid out of the eye.

In the context of medical terminology, "lenses" generally refers to optical lenses used in various medical devices and instruments. These lenses are typically made of glass or plastic and are designed to refract (bend) light in specific ways to help magnify, focus, or redirect images. Here are some examples:

1. In ophthalmology and optometry, lenses are used in eyeglasses, contact lenses, and ophthalmic instruments to correct vision problems like myopia (nearsightedness), hypermetropia (farsightedness), astigmatism, or presbyopia.
2. In surgical microscopes, lenses are used to provide a magnified and clear view of the operating field during microsurgical procedures like ophthalmic, neurosurgical, or ENT (Ear, Nose, Throat) surgeries.
3. In endoscopes and laparoscopes, lenses are used to transmit light and images from inside the body during minimally invasive surgical procedures.
4. In ophthalmic diagnostic instruments like slit lamps, lenses are used to examine various structures of the eye in detail.

In summary, "lenses" in medical terminology refer to optical components that help manipulate light to aid in diagnosis, treatment, or visual correction.

Geographic atrophy is a medical term used to describe a specific pattern of degeneration of the retinal pigment epithelium (RPE) and the underlying choroidal tissue in the eye. This condition is often associated with age-related macular degeneration (AMD), which is a leading cause of vision loss in older adults.

In geographic atrophy, there are well-defined areas of RPE and choroidal atrophy that appear as pale, irregularly shaped patches in the central part of the retina known as the macula. These patches can grow larger over time and may lead to progressive vision loss. The exact cause of geographic atrophy is not fully understood, but it is thought to be related to oxidative stress, inflammation, and other age-related changes in the eye.

Currently, there are no effective treatments for geographic atrophy, although research is ongoing to find new ways to slow or halt its progression. Regular eye exams and monitoring by an ophthalmologist are important for people with AMD or geographic atrophy to help detect any changes in their vision and manage their condition effectively.

Vision disorders refer to a wide range of conditions that affect the visual system and result in various symptoms, such as blurry vision, double vision, distorted vision, impaired depth perception, and difficulty with visual tracking or focusing. These disorders can be categorized into several types, including:

1. Refractive errors: These occur when the shape of the eye prevents light from focusing directly on the retina, resulting in blurry vision. Examples include myopia (nearsightedness), hyperopia (farsightedness), astigmatism, and presbyopia (age-related loss of near vision).
2. Strabismus: Also known as crossed eyes or walleye, strabismus is a misalignment of the eyes where they point in different directions, which can lead to double vision or loss of depth perception.
3. Amblyopia: Often called lazy eye, amblyopia is a condition where one eye has reduced vision due to lack of proper visual development during childhood. It may be caused by strabismus, refractive errors, or other factors that interfere with normal visual development.
4. Accommodative disorders: These involve problems with the focusing ability of the eyes, such as convergence insufficiency (difficulty focusing on close objects) and accommodative dysfunction (inability to maintain clear vision at different distances).
5. Binocular vision disorders: These affect how the eyes work together as a team, leading to issues like poor depth perception, eye strain, and headaches. Examples include convergence insufficiency, divergence excess, and suppression.
6. Ocular motility disorders: These involve problems with eye movement, such as nystagmus (involuntary eye movements), strabismus, or restricted extraocular muscle function.
7. Visual processing disorders: These affect the brain's ability to interpret and make sense of visual information, even when the eyes themselves are healthy. Symptoms may include difficulty with reading, recognizing shapes and objects, and understanding spatial relationships.
8. Low vision: This term refers to significant visual impairment that cannot be fully corrected with glasses, contact lenses, medication, or surgery. It includes conditions like macular degeneration, diabetic retinopathy, glaucoma, and cataracts.
9. Blindness: Complete loss of sight in both eyes, which can be caused by various factors such as injury, disease, or genetic conditions.

Retinoscopy is a diagnostic technique used in optometry and ophthalmology to estimate the refractive error of the eye, or in other words, to determine the prescription for eyeglasses or contact lenses. This procedure involves shining a light into the patient's pupil and observing the reflection off the retina while introducing different lenses in front of the patient's eye. The examiner then uses specific movements and observations to determine the amount and type of refractive error, such as myopia (nearsightedness), hyperopia (farsightedness), astigmatism, or presbyopia. Retinoscopy is a fundamental skill for eye care professionals and helps ensure that patients receive accurate prescriptions for corrective lenses.

Cone-beam computed tomography (CBCT) is a medical imaging technique that uses a cone-shaped X-ray beam to create detailed, cross-sectional images of the body. In dental and maxillofacial radiology, CBCT is used to produce three-dimensional images of the teeth, jaws, and surrounding bones.

CBCT differs from traditional computed tomography (CT) in that it uses a cone-shaped X-ray beam instead of a fan-shaped beam, which allows for a faster scan time and lower radiation dose. The X-ray beam is rotated around the patient's head, capturing data from multiple angles, which is then reconstructed into a three-dimensional image using specialized software.

CBCT is commonly used in dental implant planning, orthodontic treatment planning, airway analysis, and the diagnosis and management of jaw pathologies such as tumors and fractures. It provides detailed information about the anatomy of the teeth, jaws, and surrounding structures, which can help clinicians make more informed decisions about patient care.

However, it is important to note that CBCT should only be used when necessary, as it still involves exposure to ionizing radiation. The benefits of using CBCT must be weighed against the potential risks associated with radiation exposure.

Electron microscope tomography (EMT) is a 3D imaging technique used in electron microscopy. It involves collecting a series of images of a sample at different tilt angles, and then using computational algorithms to reconstruct the 3D structure of the sample from these images.

In EMT, a sample is prepared and placed in an electron microscope, where it is exposed to a beam of electrons. The electrons interact with the atoms in the sample, producing contrast that allows the features of the sample to be visualized. By tilting the sample and collecting images at multiple angles, a range of perspectives can be obtained, which are then used to create a 3D reconstruction of the sample.

EMT is a powerful tool for studying the ultrastructure of cells and tissues, as it allows researchers to visualize structures that may not be visible using other imaging techniques. It has been used to study a wide range of biological systems, including viruses, bacteria, organelles, and cells.

EMT is a complex technique that requires specialized equipment and expertise to perform. However, it can provide valuable insights into the structure and function of biological systems, making it an important tool in the field of biology and medicine.

A laser is not a medical term per se, but a physical concept that has important applications in medicine. The term "LASER" stands for "Light Amplification by Stimulated Emission of Radiation." It refers to a device that produces and amplifies light with specific characteristics, such as monochromaticity (single wavelength), coherence (all waves moving in the same direction), and high intensity.

In medicine, lasers are used for various therapeutic and diagnostic purposes, including surgery, dermatology, ophthalmology, and dentistry. They can be used to cut, coagulate, or vaporize tissues with great precision, minimizing damage to surrounding structures. Additionally, lasers can be used to detect and measure physiological parameters, such as blood flow and oxygen saturation.

It's important to note that while lasers are powerful tools in medicine, they must be used by trained professionals to ensure safe and effective treatment.

The Doppler effect, also known as the Doppler shift, is a change in frequency or wavelength of a wave in relation to an observer who is moving relative to the source of the wave. It was first described by Austrian physicist Christian Doppler in 1842.

In the context of medical ultrasound, the Doppler effect is used to measure the velocity of blood flow in the body. When the ultrasound waves encounter moving red blood cells, the frequency of the reflected waves changes due to the Doppler effect. This change in frequency can be used to calculate the speed and direction of blood flow.

Doppler ultrasound is commonly used in medical imaging to assess conditions such as heart valve function, blood clots, and narrowed or blocked blood vessels. It can also be used to monitor fetal heart rate and blood flow during pregnancy.

"Body weights and measures" is a general term that refers to the various methods used to quantify an individual's physical characteristics, particularly those related to health and fitness. This can include:

1. Body weight: The total amount of weight that a person's body possesses, typically measured in pounds or kilograms.
2. Height: The vertical distance from the bottom of the feet to the top of the head, usually measured in inches or centimeters.
3. Blood pressure: The force exerted by the blood on the walls of the arteries as it circulates through the body, typically measured in millimeters of mercury (mmHg).
4. Body mass index (BMI): A measure of body fat based on an individual's weight and height, calculated by dividing a person's weight in kilograms by their height in meters squared.
5. Waist circumference: The distance around the narrowest part of the waist, typically measured at the level of the belly button.
6. Hip circumference: The distance around the widest part of the hips, usually measured at the level of the greatest protrusion of the buttocks.
7. Blood glucose levels: The concentration of glucose in the blood, typically measured in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L).
8. Cholesterol levels: The amount of cholesterol present in the blood, usually measured in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L).

These and other body weights and measures are commonly used by healthcare professionals to assess an individual's health status, identify potential health risks, and guide treatment decisions.

Coronary vessels refer to the network of blood vessels that supply oxygenated blood and nutrients to the heart muscle, also known as the myocardium. The two main coronary arteries are the left main coronary artery and the right coronary artery.

The left main coronary artery branches off into the left anterior descending artery (LAD) and the left circumflex artery (LCx). The LAD supplies blood to the front of the heart, while the LCx supplies blood to the side and back of the heart.

The right coronary artery supplies blood to the right lower part of the heart, including the right atrium and ventricle, as well as the back of the heart.

Coronary vessel disease (CVD) occurs when these vessels become narrowed or blocked due to the buildup of plaque, leading to reduced blood flow to the heart muscle. This can result in chest pain, shortness of breath, or a heart attack.

In the field of medical imaging, "phantoms" refer to physical objects that are specially designed and used for calibration, quality control, and evaluation of imaging systems. These phantoms contain materials with known properties, such as attenuation coefficients or spatial resolution, which allow for standardized measurement and comparison of imaging parameters across different machines and settings.

Imaging phantoms can take various forms depending on the modality of imaging. For example, in computed tomography (CT), a common type of phantom is the "water-equivalent phantom," which contains materials with similar X-ray attenuation properties as water. This allows for consistent measurement of CT dose and image quality. In magnetic resonance imaging (MRI), phantoms may contain materials with specific relaxation times or magnetic susceptibilities, enabling assessment of signal-to-noise ratio, spatial resolution, and other imaging parameters.

By using these standardized objects, healthcare professionals can ensure the accuracy, consistency, and reliability of medical images, ultimately contributing to improved patient care and safety.

Observer variation, also known as inter-observer variability or measurement agreement, refers to the difference in observations or measurements made by different observers or raters when evaluating the same subject or phenomenon. It is a common issue in various fields such as medicine, research, and quality control, where subjective assessments are involved.

In medical terms, observer variation can occur in various contexts, including:

1. Diagnostic tests: Different radiologists may interpret the same X-ray or MRI scan differently, leading to variations in diagnosis.
2. Clinical trials: Different researchers may have different interpretations of clinical outcomes or adverse events, affecting the consistency and reliability of trial results.
3. Medical records: Different healthcare providers may document medical histories, physical examinations, or treatment plans differently, leading to inconsistencies in patient care.
4. Pathology: Different pathologists may have varying interpretations of tissue samples or laboratory tests, affecting diagnostic accuracy.

Observer variation can be minimized through various methods, such as standardized assessment tools, training and calibration of observers, and statistical analysis of inter-rater reliability.

The optic nerve, also known as the second cranial nerve, is the nerve that transmits visual information from the retina to the brain. It is composed of approximately one million nerve fibers that carry signals related to vision, such as light intensity and color, from the eye's photoreceptor cells (rods and cones) to the visual cortex in the brain. The optic nerve is responsible for carrying this visual information so that it can be processed and interpreted by the brain, allowing us to see and perceive our surroundings. Damage to the optic nerve can result in vision loss or impairment.

Laser coagulation, also known as laser photocoagulation, is a medical procedure that uses a laser to seal or destroy abnormal blood vessels or tissue. The laser produces a concentrated beam of light that can be precisely focused on the target area. When the laser energy is absorbed by the tissue, it causes the temperature to rise, which leads to coagulation (the formation of a clot) or destruction of the tissue.

In ophthalmology, laser coagulation is commonly used to treat conditions such as diabetic retinopathy, age-related macular degeneration, and retinal tears or holes. The procedure can help to seal leaking blood vessels, reduce fluid leakage, and prevent further vision loss. It is usually performed as an outpatient procedure and may be repeated if necessary.

In other medical specialties, laser coagulation may be used to control bleeding, destroy tumors, or remove unwanted tissue. The specific technique and parameters of the laser treatment will depend on the individual patient's needs and the condition being treated.

Central serous chorioretinopathy (CSC) is a medical condition that affects the eye, specifically the retina and the choroid. The choroid is the layer of blood vessels that supplies oxygen and nutrients to the retina. In CSC, there is a buildup of fluid under the retina, leading to distortion or loss of vision.

The term "central" in CSC refers to the fact that the fluid accumulation occurs in the central part of the retina, called the macula, which is responsible for sharp, detailed vision. The term "serous" indicates that the fluid accumulation is made up of serum, the clear portion of blood.

CSC is more common in middle-aged men and can be associated with stress, corticosteroid use, and certain medical conditions such as hypertension and sleep apnea. In many cases, CSC resolves on its own within a few months without treatment. However, some people may experience recurrent episodes or develop chronic CSC, which can lead to permanent vision loss if left untreated. Treatment options for CSC include laser therapy, photodynamic therapy, and medication.

Scanning Laser Polarimetry (SLP) is not primarily a medical term, but a technique that has been applied in medical research and diagnostics. It's a non-invasive method used to analyze the polarization of light as it interacts with biological tissues.

In a simpler sense, SLP uses laser light, which is polarized (meaning all the light waves vibrate in the same plane), to scan tissue. As this light interacts with the tissue, changes in the polarization of the light can occur due to various factors such as the structure and composition of the tissue. By analyzing these changes, SLP can provide information about the tissue's properties, which can be useful in the detection and diagnosis of certain medical conditions.

For example, it has been used in research related to diagnosing diseases like glaucoma and Alzheimer's disease by analyzing the polarization changes in the eye's retina and the brain's cortex, respectively. However, it's important to note that while SLP has shown promise in these areas, it is not yet widely used in clinical settings.

Ocular tonometry is a medical test used to measure the pressure inside the eye, also known as intraocular pressure (IOP). This test is an essential part of diagnosing and monitoring glaucoma, a group of eye conditions that can cause vision loss and blindness due to damage to the optic nerve from high IOP.

The most common method of ocular tonometry involves using a tonometer device that gently touches the front surface of the eye (cornea) with a small probe or prism. The device measures the amount of force required to flatten the cornea slightly, which correlates with the pressure inside the eye. Other methods of ocular tonometry include applanation tonometry, which uses a small amount of fluorescein dye and a blue light to measure the IOP, and rebound tonometry, which uses a lightweight probe that briefly touches the cornea and then bounces back to determine the IOP.

Regular ocular tonometry is important for detecting glaucoma early and preventing vision loss. It is typically performed during routine eye exams and may be recommended more frequently for individuals at higher risk of developing glaucoma, such as those with a family history of the condition or certain medical conditions like diabetes.

Biometry, also known as biometrics, is the scientific study of measurements and statistical analysis of living organisms. In a medical context, biometry is often used to refer to the measurement and analysis of physical characteristics or features of the human body, such as height, weight, blood pressure, heart rate, and other physiological variables. These measurements can be used for a variety of purposes, including diagnosis, treatment planning, monitoring disease progression, and research.

In addition to physical measurements, biometry may also refer to the use of statistical methods to analyze biological data, such as genetic information or medical images. This type of analysis can help researchers and clinicians identify patterns and trends in large datasets, and make predictions about health outcomes or treatment responses.

Overall, biometry is an important tool in modern medicine, as it allows healthcare professionals to make more informed decisions based on data and evidence.

Ocular hypertension is a medical condition characterized by elevated pressure within the eye (intraocular pressure or IOP), which is higher than normal but not necessarily high enough to cause any visible damage to the optic nerve or visual field loss. It serves as a significant risk factor for developing glaucoma, a sight-threatening disease.

The normal range of intraocular pressure is typically between 10-21 mmHg (millimeters of mercury). Ocular hypertension is often defined as an IOP consistently above 21 mmHg, although some studies suggest that even pressures between 22-30 mmHg may not cause damage in all individuals. Regular monitoring and follow-up with an ophthalmologist are essential for people diagnosed with ocular hypertension to ensure early detection and management of any potential glaucomatous changes. Treatment options include medications, laser therapy, or surgery to lower the IOP and reduce the risk of glaucoma onset.

Diagnostic imaging is a medical specialty that uses various technologies to produce visual representations of the internal structures and functioning of the body. These images are used to diagnose injury, disease, or other abnormalities and to monitor the effectiveness of treatment. Common modalities of diagnostic imaging include:

1. Radiography (X-ray): Uses ionizing radiation to produce detailed images of bones, teeth, and some organs.
2. Computed Tomography (CT) Scan: Combines X-ray technology with computer processing to create cross-sectional images of the body.
3. Magnetic Resonance Imaging (MRI): Uses a strong magnetic field and radio waves to generate detailed images of soft tissues, organs, and bones.
4. Ultrasound: Employs high-frequency sound waves to produce real-time images of internal structures, often used for obstetrics and gynecology.
5. Nuclear Medicine: Involves the administration of radioactive tracers to assess organ function or detect abnormalities within the body.
6. Positron Emission Tomography (PET) Scan: Uses a small amount of radioactive material to produce detailed images of metabolic activity in the body, often used for cancer detection and monitoring treatment response.
7. Fluoroscopy: Utilizes continuous X-ray imaging to observe moving structures or processes within the body, such as swallowing studies or angiography.

Diagnostic imaging plays a crucial role in modern medicine, allowing healthcare providers to make informed decisions about patient care and treatment plans.

Retrospective studies, also known as retrospective research or looking back studies, are a type of observational study that examines data from the past to draw conclusions about possible causal relationships between risk factors and outcomes. In these studies, researchers analyze existing records, medical charts, or previously collected data to test a hypothesis or answer a specific research question.

Retrospective studies can be useful for generating hypotheses and identifying trends, but they have limitations compared to prospective studies, which follow participants forward in time from exposure to outcome. Retrospective studies are subject to biases such as recall bias, selection bias, and information bias, which can affect the validity of the results. Therefore, retrospective studies should be interpreted with caution and used primarily to generate hypotheses for further testing in prospective studies.

Drug-eluting stents (DES) are medical devices used in the treatment of coronary artery disease. They are small, flexible tubes that are coated with a medication that is slowly released (eluted) over time to prevent the formation of scar tissue and reduce the risk of renarrowing (restenosis) of the artery after it has been treated with angioplasty and stenting.

The stent is typically placed in a narrowed or blocked coronary artery during a percutaneous coronary intervention (PCI) procedure, such as angioplasty, to open up the blood vessel and improve blood flow to the heart muscle. The medication on the DES helps to prevent the growth of smooth muscle cells and the formation of scar tissue in the artery, which can cause restenosis and require additional treatments.

The most commonly used medications on DES are sirolimus, paclitaxel, zotarolimus, and everolimus. These drugs work by inhibiting the growth of smooth muscle cells and reducing inflammation in the artery. While DES have been shown to reduce the risk of restenosis compared to bare-metal stents, they also carry a small increased risk of late stent thrombosis (blood clots forming in the stent), which can lead to serious complications such as heart attack or stroke. Therefore, patients who receive DES are typically prescribed long-term antiplatelet therapy to reduce this risk.

Birefringence is a property of certain materials, such as crystals and some plastics, to split a beam of light into two separate beams with different polarization states and refractive indices when the light passes through the material. This phenomenon arises due to the anisotropic structure of these materials, where their physical properties vary depending on the direction of measurement.

When a unpolarized or partially polarized light beam enters a birefringent material, it gets separated into two orthogonally polarized beams called the ordinary and extraordinary rays. These rays propagate through the material at different speeds due to their distinct refractive indices, resulting in a phase delay between them. Upon exiting the material, the recombination of these two beams can produce various optical effects, such as double refraction or interference patterns, depending on the thickness and orientation of the birefringent material and the polarization state of the incident light.

Birefringence has numerous applications in optics, including waveplates, polarizing filters, stress analysis, and microscopy techniques like phase contrast and differential interference contrast imaging.

An artifact, in the context of medical terminology, refers to something that is created or introduced during a scientific procedure or examination that does not naturally occur in the patient or specimen being studied. Artifacts can take many forms and can be caused by various factors, including contamination, damage, degradation, or interference from equipment or external sources.

In medical imaging, for example, an artifact might appear as a distortion or anomaly on an X-ray, MRI, or CT scan that is not actually present in the patient's body. This can be caused by factors such as patient movement during the scan, metal implants or other foreign objects in the body, or issues with the imaging equipment itself.

Similarly, in laboratory testing, an artifact might refer to a substance or characteristic that is introduced into a sample during collection, storage, or analysis that can interfere with accurate results. This could include things like contamination from other samples, degradation of the sample over time, or interference from chemicals used in the testing process.

In general, artifacts are considered to be sources of error or uncertainty in medical research and diagnosis, and it is important to identify and account for them in order to ensure accurate and reliable results.

Intraocular injections are a type of medical procedure where medication is administered directly into the eye. This technique is often used to deliver drugs that treat various eye conditions, such as age-related macular degeneration, diabetic retinopathy, and endophthalmitis. The most common type of intraocular injection is an intravitreal injection, which involves injecting medication into the vitreous cavity, the space inside the eye filled with a clear gel-like substance called the vitreous humor. This procedure is typically performed by an ophthalmologist in a clinical setting and may be repeated at regular intervals depending on the condition being treated.

Follow-up studies are a type of longitudinal research that involve repeated observations or measurements of the same variables over a period of time, in order to understand their long-term effects or outcomes. In medical context, follow-up studies are often used to evaluate the safety and efficacy of medical treatments, interventions, or procedures.

In a typical follow-up study, a group of individuals (called a cohort) who have received a particular treatment or intervention are identified and then followed over time through periodic assessments or data collection. The data collected may include information on clinical outcomes, adverse events, changes in symptoms or functional status, and other relevant measures.

The results of follow-up studies can provide important insights into the long-term benefits and risks of medical interventions, as well as help to identify factors that may influence treatment effectiveness or patient outcomes. However, it is important to note that follow-up studies can be subject to various biases and limitations, such as loss to follow-up, recall bias, and changes in clinical practice over time, which must be carefully considered when interpreting the results.

Optic neuritis is a medical condition characterized by inflammation and damage to the optic nerve, which transmits visual information from the eye to the brain. This condition can result in various symptoms such as vision loss, pain with eye movement, color vision disturbances, and pupillary abnormalities. Optic neuritis may occur in isolation or be associated with other underlying medical conditions, including multiple sclerosis, neuromyelitis optica, and autoimmune disorders. The diagnosis typically involves a comprehensive eye examination, including visual acuity testing, dilated funduscopic examination, and possibly imaging studies like MRI to evaluate the optic nerve and brain. Treatment options may include corticosteroids or other immunomodulatory therapies to reduce inflammation and prevent further damage to the optic nerve.

Myopia, also known as nearsightedness, is a common refractive error of the eye. It occurs when the eye is either too long or the cornea (the clear front part of the eye) is too curved. As a result, light rays focus in front of the retina instead of directly on it, causing distant objects to appear blurry while close objects remain clear.

Myopia typically develops during childhood and can progress gradually or rapidly until early adulthood. It can be corrected with glasses, contact lenses, or refractive surgery such as LASIK. Regular eye examinations are essential for people with myopia to monitor any changes in their prescription and ensure proper correction.

While myopia is generally not a serious condition, high levels of nearsightedness can increase the risk of certain eye diseases, including cataracts, glaucoma, retinal detachment, and myopic degeneration. Therefore, it's crucial to manage myopia effectively and maintain regular follow-ups with an eye care professional.

Optic atrophy is a medical term that refers to the degeneration and shrinkage (atrophy) of the optic nerve, which transmits visual information from the eye to the brain. This condition can result in various vision abnormalities, including loss of visual acuity, color vision deficiencies, and peripheral vision loss.

Optic atrophy can occur due to a variety of causes, such as:

* Traumatic injuries to the eye or optic nerve
* Glaucoma
* Optic neuritis (inflammation of the optic nerve)
* Ischemic optic neuropathy (reduced blood flow to the optic nerve)
* Compression or swelling of the optic nerve
* Hereditary or congenital conditions affecting the optic nerve
* Toxins and certain medications that can damage the optic nerve.

The diagnosis of optic atrophy typically involves a comprehensive eye examination, including visual acuity testing, refraction assessment, slit-lamp examination, and dilated funduscopic examination to evaluate the health of the optic nerve. In some cases, additional diagnostic tests such as visual field testing, optical coherence tomography (OCT), or magnetic resonance imaging (MRI) may be necessary to confirm the diagnosis and determine the underlying cause.

There is no specific treatment for optic atrophy, but addressing the underlying cause can help prevent further damage to the optic nerve. In some cases, vision rehabilitation may be recommended to help patients adapt to their visual impairment.

Corneal topography is a non-invasive medical imaging technique used to create a detailed map of the surface curvature of the cornea, which is the clear, dome-shaped surface at the front of the eye. This procedure provides valuable information about the shape and condition of the cornea, helping eye care professionals assess various eye conditions such as astigmatism, keratoconus, and other corneal abnormalities. It can also be used in contact lens fitting, refractive surgery planning, and post-surgical evaluation.

Indocyanine green (ICG) is a sterile, water-soluble, tricarbocyanine dye that is used as a diagnostic agent in medical imaging. It is primarily used in ophthalmology for fluorescein angiography to examine blood flow in the retina and choroid, and in cardiac surgery to assess cardiac output and perfusion. When injected into the body, ICG binds to plasma proteins and fluoresces when exposed to near-infrared light, allowing for visualization of various tissues and structures. It is excreted primarily by the liver and has a half-life of approximately 3-4 minutes in the bloodstream.

Wet macular degeneration, also known as neovascular or exudative age-related macular degeneration (AMD), is a medical condition that affects the central part of the retina called the macula. It's characterized by the growth of new blood vessels (neovascularization) from the choroid layer behind the retina into the macula, which is not typical in healthy eyes. These abnormal blood vessels are fragile and prone to leakage, leading to the accumulation of fluid or blood in the macula, causing distortion or loss of central vision.

The wet form of AMD can progress rapidly and often leads to more severe visual loss compared to the dry form. It's essential to diagnose and treat wet AMD promptly to preserve as much vision as possible. Common treatments include anti-vascular endothelial growth factor (VEGF) injections, photodynamic therapy, or thermal laser treatment, depending on the specific case and individual patient factors.

X-ray tomography, also known as computed tomography (CT) or computerized axial tomography (CAT), is a medical imaging technique that uses X-rays to create detailed cross-sectional images of the body. In this technique, an X-ray source and detectors rotate around the patient, acquiring multiple X-ray projections at different angles. A computer then processes these projections to reconstruct tomographic images (slices) of the internal structures of the body, such as bones, organs, and soft tissues.

The term "tomography" comes from the Greek words "tome," meaning slice or section, and "graphein," meaning to write or record. X-ray tomography allows radiologists and other medical professionals to visualize and diagnose various conditions, such as fractures, tumors, infections, and internal injuries, more accurately and efficiently than with traditional X-ray imaging techniques.

It is important to note that while X-ray tomography provides valuable diagnostic information, it does involve exposure to ionizing radiation. Therefore, the benefits of the examination should outweigh the potential risks, and the use of this technique should be justified based on clinical necessity and patient safety considerations.

Coronary artery disease (CAD) is a medical condition in which the coronary arteries, which supply oxygen-rich blood to the heart muscle, become narrowed or blocked due to the buildup of cholesterol, fatty deposits, and other substances, known as plaque. Over time, this buildup can cause the arteries to harden and narrow (a process called atherosclerosis), reducing blood flow to the heart muscle.

The reduction in blood flow can lead to various symptoms and complications, including:

1. Angina (chest pain or discomfort) - This occurs when the heart muscle doesn't receive enough oxygen-rich blood, causing pain, pressure, or discomfort in the chest, arms, neck, jaw, or back.
2. Shortness of breath - When the heart isn't receiving adequate blood flow, it can't pump blood efficiently to meet the body's demands, leading to shortness of breath during physical activities or at rest.
3. Heart attack - If a piece of plaque ruptures or breaks off in a coronary artery, a blood clot can form and block the artery, causing a heart attack (myocardial infarction). This can damage or destroy part of the heart muscle.
4. Heart failure - Chronic reduced blood flow to the heart muscle can weaken it over time, leading to heart failure, a condition in which the heart can't pump blood efficiently to meet the body's needs.
5. Arrhythmias - Reduced blood flow and damage to the heart muscle can lead to abnormal heart rhythms (arrhythmias), which can be life-threatening if not treated promptly.

Coronary artery disease is typically diagnosed through a combination of medical history, physical examination, and diagnostic tests such as electrocardiograms (ECGs), stress testing, cardiac catheterization, and imaging studies like coronary computed tomography angiography (CCTA). Treatment options for CAD include lifestyle modifications, medications, medical procedures, and surgery.

Retinal vessels refer to the blood vessels that are located in the retina, which is the light-sensitive tissue that lines the inner surface of the eye. The retina contains two types of blood vessels: arteries and veins.

The central retinal artery supplies oxygenated blood to the inner layers of the retina, while the central retinal vein drains deoxygenated blood from the retina. These vessels can be visualized during a routine eye examination using an ophthalmoscope, which allows healthcare professionals to assess their health and any potential abnormalities.

Retinal vessels are essential for maintaining the health and function of the retina, and any damage or changes to these vessels can affect vision and lead to various eye conditions such as diabetic retinopathy, retinal vein occlusion, and hypertensive retinopathy.

The Predictive Value of Tests, specifically the Positive Predictive Value (PPV) and Negative Predictive Value (NPV), are measures used in diagnostic tests to determine the probability that a positive or negative test result is correct.

Positive Predictive Value (PPV) is the proportion of patients with a positive test result who actually have the disease. It is calculated as the number of true positives divided by the total number of positive results (true positives + false positives). A higher PPV indicates that a positive test result is more likely to be a true positive, and therefore the disease is more likely to be present.

Negative Predictive Value (NPV) is the proportion of patients with a negative test result who do not have the disease. It is calculated as the number of true negatives divided by the total number of negative results (true negatives + false negatives). A higher NPV indicates that a negative test result is more likely to be a true negative, and therefore the disease is less likely to be present.

The predictive value of tests depends on the prevalence of the disease in the population being tested, as well as the sensitivity and specificity of the test. A test with high sensitivity and specificity will generally have higher predictive values than a test with low sensitivity and specificity. However, even a highly sensitive and specific test can have low predictive values if the prevalence of the disease is low in the population being tested.

Absorbable implants are medical devices that are designed to be placed inside the body during a surgical procedure, where they provide support, stabilization, or other functions, and then gradually break down and are absorbed by the body over time. These implants are typically made from materials such as polymers, proteins, or ceramics that have been engineered to degrade at a controlled rate, allowing them to be resorbed and eliminated from the body without the need for a second surgical procedure to remove them.

Absorbable implants are often used in orthopedic, dental, and plastic surgery applications, where they can help promote healing and support tissue regeneration. For example, absorbable screws or pins may be used to stabilize fractured bones during the healing process, after which they will gradually dissolve and be absorbed by the body. Similarly, absorbable membranes may be used in dental surgery to help guide the growth of new bone and gum tissue around an implant, and then be resorbed over time.

It's important to note that while absorbable implants offer several advantages over non-absorbable materials, such as reduced risk of infection and improved patient comfort, they may also have some limitations. For example, the mechanical properties of absorbable materials may not be as strong as those of non-absorbable materials, which could affect their performance in certain applications. Additionally, the degradation products of absorbable implants may cause local inflammation or other adverse reactions in some patients. As with any medical device, the use of absorbable implants should be carefully considered and discussed with a qualified healthcare professional.

Retinal dystrophies are a group of genetic eye disorders that primarily affect the retina, a light-sensitive layer at the back of the eye. These conditions are characterized by progressive degeneration and death of photoreceptor cells (rods and cones) in the retina, leading to vision loss.

The term "dystrophy" refers to a condition that results from the abnormal or defective development and function of tissues or organs. In the case of retinal dystrophies, the photoreceptor cells do not develop or function properly, resulting in visual impairment.

Retinal dystrophies can present at any age, from infancy to adulthood, and can have varying degrees of severity. Some common symptoms include night blindness, decreased visual acuity, loss of peripheral vision, light sensitivity, and color vision abnormalities.

Examples of retinal dystrophies include retinitis pigmentosa, Stargardt disease, Usher syndrome, and Leber congenital amaurosis, among others. These conditions are typically inherited and can be caused by mutations in various genes that play a role in the development and function of the retina.

There is currently no cure for retinal dystrophies, but research is ongoing to develop treatments that may slow or halt the progression of these conditions, such as gene therapy and stem cell transplantation.

In medical terms, the iris refers to the colored portion of the eye that surrounds the pupil. It is a circular structure composed of thin, contractile muscle fibers (radial and circumferential) arranged in a regular pattern. These muscles are controlled by the autonomic nervous system and can adjust the size of the pupil in response to changes in light intensity or emotional arousal. By constricting or dilating the iris, the amount of light entering the eye can be regulated, which helps maintain optimal visual acuity under various lighting conditions.

The color of the iris is determined by the concentration and distribution of melanin pigments within the iris stroma. The iris also contains blood vessels, nerves, and connective tissue that support its structure and function. Anatomically, the iris is continuous with the ciliary body and the choroid, forming part of the uveal tract in the eye.

Retinitis pigmentosa (RP) is a group of rare, genetic disorders that involve a breakdown and loss of cells in the retina - a light-sensitive tissue located at the back of the eye. The retina converts light into electrical signals which are then sent to the brain and interpreted as visual images.

In RP, the cells that detect light (rods and cones) degenerate more slowly than other cells in the retina, leading to a progressive loss of vision. Symptoms typically begin in childhood with night blindness (difficulty seeing in low light), followed by a gradual narrowing of the visual field (tunnel vision). Over time, this can lead to significant vision loss and even blindness.

The condition is usually inherited and there are several different genes that have been associated with RP. The diagnosis is typically made based on a combination of genetic testing, family history, and clinical examination. Currently, there is no cure for RP, but researchers are actively working to develop new treatments that may help slow or stop the progression of the disease.

Fiber optic technology in the medical context refers to the use of thin, flexible strands of glass or plastic fibers that are designed to transmit light and images along their length. These fibers are used to create bundles, known as fiber optic cables, which can be used for various medical applications such as:

1. Illumination: Fiber optics can be used to deliver light to hard-to-reach areas during surgical procedures or diagnostic examinations.
2. Imaging: Fiber optics can transmit images from inside the body, enabling doctors to visualize internal structures and tissues. This is commonly used in medical imaging techniques such as endoscopy, colonoscopy, and laparoscopy.
3. Sensing: Fiber optic sensors can be used to measure various physiological parameters such as temperature, pressure, and strain within the body. These sensors can provide real-time data during surgical procedures or for monitoring patients' health status.

Fiber optic technology offers several advantages over traditional medical imaging techniques, including high resolution, flexibility, small diameter, and the ability to bend around corners without significant loss of image quality. Additionally, fiber optics are non-magnetic and can be used in MRI environments without causing interference.

Atherosclerotic plaque is a deposit of fatty (cholesterol and fat) substances, calcium, and other substances in the inner lining of an artery. This plaque buildup causes the artery to narrow and harden, reducing blood flow through the artery, which can lead to serious cardiovascular conditions such as coronary artery disease, angina, heart attack, or stroke. The process of atherosclerosis develops gradually over decades and can start in childhood.

Triamcinolone Acetonide is a synthetic glucocorticoid, which is a class of corticosteroids. It is used in the form of topical creams, ointments, and sprays to reduce skin inflammation, itching, and allergies. It can also be administered through injection for the treatment of various conditions such as arthritis, bursitis, and tendonitis. Triamcinolone Acetonide works by suppressing the immune system's response, reducing inflammation, and blocking the production of substances that cause allergies.

It is important to note that prolonged use or overuse of triamcinolone acetonide can lead to side effects such as thinning of the skin, easy bruising, and increased susceptibility to infections. Therefore, it should be used under the guidance of a healthcare professional.

An iridectomy is a surgical procedure that involves removing a small portion of the iris, which is the colored part of the eye. This procedure is typically performed to treat conditions such as closed-angle glaucoma or to prevent the development of acute angle closure glaucoma. By creating an opening in the iris, the surgery helps to improve the flow of fluid within the eye and reduce pressure inside the eye. It is usually done using a laser (laser iridectomy) or with surgical instruments (surgical iridectomy).

Retinal degeneration is a broad term that refers to the progressive loss of photoreceptor cells (rods and cones) in the retina, which are responsible for converting light into electrical signals that are sent to the brain. This process can lead to vision loss or blindness. There are many different types of retinal degeneration, including age-related macular degeneration, retinitis pigmentosa, and Stargardt's disease, among others. These conditions can have varying causes, such as genetic mutations, environmental factors, or a combination of both. Treatment options vary depending on the specific type and progression of the condition.

Microscopy is a technical field in medicine that involves the use of microscopes to observe structures and phenomena that are too small to be seen by the naked eye. It allows for the examination of samples such as tissues, cells, and microorganisms at high magnifications, enabling the detection and analysis of various medical conditions, including infections, diseases, and cellular abnormalities.

There are several types of microscopy used in medicine, including:

1. Light Microscopy: This is the most common type of microscopy, which uses visible light to illuminate and magnify samples. It can be used to examine a wide range of biological specimens, such as tissue sections, blood smears, and bacteria.
2. Electron Microscopy: This type of microscopy uses a beam of electrons instead of light to produce highly detailed images of samples. It is often used in research settings to study the ultrastructure of cells and tissues.
3. Fluorescence Microscopy: This technique involves labeling specific molecules within a sample with fluorescent dyes, allowing for their visualization under a microscope. It can be used to study protein interactions, gene expression, and cell signaling pathways.
4. Confocal Microscopy: This type of microscopy uses a laser beam to scan a sample point by point, producing high-resolution images with reduced background noise. It is often used in medical research to study the structure and function of cells and tissues.
5. Scanning Probe Microscopy: This technique involves scanning a sample with a physical probe, allowing for the measurement of topography, mechanical properties, and other characteristics at the nanoscale. It can be used in medical research to study the structure and function of individual molecules and cells.

Coronary angiography is a medical procedure that uses X-ray imaging to visualize the coronary arteries, which supply blood to the heart muscle. During the procedure, a thin, flexible catheter is inserted into an artery in the arm or groin and threaded through the blood vessels to the heart. A contrast dye is then injected through the catheter, and X-ray images are taken as the dye flows through the coronary arteries. These images can help doctors diagnose and treat various heart conditions, such as blockages or narrowing of the arteries, that can lead to chest pain or heart attacks. It is also known as coronary arteriography or cardiac catheterization.

Ocular refraction is a medical term that refers to the bending of light as it passes through the optical media of the eye, including the cornea and lens. This process allows the eye to focus light onto the retina, creating a clear image. The refractive power of the eye is determined by the curvature and transparency of these structures.

In a normal eye, light rays are bent or refracted in such a way that they converge at a single point on the retina, producing a sharp and focused image. However, if the curvature of the cornea or lens is too steep or too flat, the light rays may not converge properly, resulting in a refractive error such as myopia (nearsightedness), hyperopia (farsightedness), or astigmatism.

Ocular refraction can be measured using a variety of techniques, including retinoscopy, automated refraction, and subjective refraction. These measurements are used to determine the appropriate prescription for corrective lenses such as eyeglasses or contact lenses. In some cases, ocular refractive errors may be corrected surgically through procedures such as LASIK or PRK.

Descemet Stripping Endothelial Keratoplasty (DSEK) is a type of corneal transplant surgery that involves replacing the damaged endothelium (inner layer) of the cornea with healthy endothelial cells from a donor. In this procedure, the surgeon removes the patient's Descemet's membrane (a thin, clear tissue beneath the endothelium) along with the damaged endothelium. Then, a thin disc of donor tissue, which includes both the endothelium and a small portion of the adjacent corneal stroma, is inserted into the eye and positioned using an air bubble. The new endothelial cells help to pump excess fluid out of the cornea, allowing it to become clear again. DSEK typically results in faster visual recovery and lower rejection rates compared to traditional full-thickness corneal transplantation.

A feasibility study is a preliminary investigation or analysis conducted to determine the viability of a proposed project, program, or product. In the medical field, feasibility studies are often conducted before implementing new treatments, procedures, equipment, or facilities. These studies help to assess the practicality and effectiveness of the proposed intervention, as well as its potential benefits and risks.

Feasibility studies in healthcare typically involve several steps:

1. Problem identification: Clearly define the problem that the proposed project, program, or product aims to address.
2. Objectives setting: Establish specific, measurable, achievable, relevant, and time-bound (SMART) objectives for the study.
3. Literature review: Conduct a thorough review of existing research and best practices related to the proposed intervention.
4. Methodology development: Design a methodology for data collection and analysis that will help answer the research questions and achieve the study's objectives.
5. Resource assessment: Evaluate the availability and adequacy of resources, including personnel, time, and finances, required to carry out the proposed intervention.
6. Risk assessment: Identify potential risks and challenges associated with the implementation of the proposed intervention and develop strategies to mitigate them.
7. Cost-benefit analysis: Estimate the costs and benefits of the proposed intervention, including direct and indirect costs, as well as short-term and long-term benefits.
8. Stakeholder engagement: Engage relevant stakeholders, such as patients, healthcare providers, administrators, and policymakers, to gather their input and support for the proposed intervention.
9. Decision-making: Based on the findings of the feasibility study, make an informed decision about whether or not to proceed with the proposed project, program, or product.

Feasibility studies are essential in healthcare as they help ensure that resources are allocated efficiently and effectively, and that interventions are evidence-based, safe, and beneficial for patients.

The sclera is the tough, white, fibrous outer coating of the eye in humans and other vertebrates, covering about five sixths of the eyeball's surface. It provides protection for the delicate inner structures of the eye and maintains its shape. The sclera is composed mainly of collagen and elastic fiber, making it strong and resilient. Its name comes from the Greek word "skleros," which means hard.

Retinal vein occlusion (RVO) is a medical condition that occurs when one of the retinal veins, which drains blood from the retina, becomes blocked by a blood clot or atherosclerotic plaque. This blockage can cause hemorrhages, fluid accumulation, and damage to the retinal tissue, leading to vision loss.

There are two types of RVO: branch retinal vein occlusion (BRVO) and central retinal vein occlusion (CRVO). BRVO affects a smaller branch retinal vein, while CRVO affects the main retinal vein. CRVO is generally associated with more severe vision loss than BRVO.

Risk factors for RVO include hypertension, diabetes, high cholesterol levels, smoking, and glaucoma. Age is also a significant risk factor, as RVO becomes more common with increasing age. Treatment options for RVO may include controlling underlying medical conditions, laser therapy, intravitreal injections of anti-VEGF agents or steroids, and surgery in some cases.

In the field of medicine, "time factors" refer to the duration of symptoms or time elapsed since the onset of a medical condition, which can have significant implications for diagnosis and treatment. Understanding time factors is crucial in determining the progression of a disease, evaluating the effectiveness of treatments, and making critical decisions regarding patient care.

For example, in stroke management, "time is brain," meaning that rapid intervention within a specific time frame (usually within 4.5 hours) is essential to administering tissue plasminogen activator (tPA), a clot-busting drug that can minimize brain damage and improve patient outcomes. Similarly, in trauma care, the "golden hour" concept emphasizes the importance of providing definitive care within the first 60 minutes after injury to increase survival rates and reduce morbidity.

Time factors also play a role in monitoring the progression of chronic conditions like diabetes or heart disease, where regular follow-ups and assessments help determine appropriate treatment adjustments and prevent complications. In infectious diseases, time factors are crucial for initiating antibiotic therapy and identifying potential outbreaks to control their spread.

Overall, "time factors" encompass the significance of recognizing and acting promptly in various medical scenarios to optimize patient outcomes and provide effective care.

Corneal edema is a medical condition characterized by the accumulation of fluid in the cornea, which is the clear, dome-shaped surface at the front of the eye. This buildup of fluid causes the cornea to swell and thicken, resulting in blurry or distorted vision. Corneal edema can be caused by various factors, including eye injuries, certain medications, eye surgeries, and diseases that affect the eye's ability to pump fluids out of the cornea. In some cases, corneal edema may resolve on its own or with treatment, but in severe cases, it may require a corneal transplant.

Polarized light microscopy is a type of microscopy that uses polarized light to enhance contrast and reveal unique optical properties in specimens. In this technique, a polarizing filter is placed under the light source, which polarizes the light as it passes through. The specimen is then illuminated with this linearly polarized light. As the light travels through the specimen, its plane of polarization may be altered due to birefringence, a property of certain materials that causes the light to split into two separate rays with different refractive indices.

A second polarizing filter, called an analyzer, is placed in the light path between the objective and the eyepiece. The orientation of this filter can be adjusted to either allow or block the transmission of light through the microscope. When the polarizer and analyzer are aligned perpendicularly, no light will pass through if the specimen does not exhibit birefringence. However, if the specimen has birefringent properties, it will cause the plane of polarization to rotate, allowing some light to pass through the analyzer and create a contrasting image.

Polarized light microscopy is particularly useful for observing structures in minerals, crystals, and certain biological materials like collagen fibers, muscle proteins, and starch granules. It can also be used to study stress patterns in plastics and other synthetic materials.

"Optical processes" is not a specific medical term, but rather a general term that refers to various phenomena and techniques involving the use of light in physics and engineering, which can have applications in medicine. Here are some examples of optical processes that may be relevant to medical fields:

1. Optical imaging: This refers to the use of light to create images of structures within the body. Examples include endoscopy, microscopy, and ophthalmoscopy.
2. Optical spectroscopy: This involves analyzing the interaction between light and matter to identify the chemical composition or physical properties of a sample. It can be used in medical diagnostics to detect abnormalities in tissues or fluids.
3. Laser therapy: Lasers are highly concentrated beams of light that can be used for a variety of medical applications, including surgery, pain relief, and skin treatments.
4. Optogenetics: This is a technique that involves using light to control the activity of specific cells in living organisms. It has potential applications in neuroscience and other fields of medicine.
5. Photodynamic therapy: This is a treatment that uses light to activate a photosensitizing agent, which then produces a chemical reaction that can destroy abnormal cells or tissues.

Overall, optical processes are an important part of many medical technologies and techniques, enabling doctors and researchers to diagnose and treat diseases with greater precision and effectiveness.

Vitreoretinal surgery is a specialized ophthalmic surgical procedure that deals with the treatment of various conditions related to the vitreous humor (the clear gel-like substance filling the space between the lens and the retina) and the retina (the light-sensitive tissue lining the inner surface of the eye). This type of surgery is typically performed by a vitreoretinal surgeon, who has additional fellowship training in this subspecialty.

The main indications for vitreoretinal surgery include:

1. Retinal detachment: A separation of the retina from its underlying tissue, which can lead to vision loss if not treated promptly.
2. Macular holes: Small breaks or tears in the center of the macula (the part of the retina responsible for sharp, central vision).
3. Epiretinal membranes: Thin layers of scar tissue that form on the surface of the retina and can distort vision.
4. Vitreous hemorrhage: Bleeding into the vitreous humor, often caused by diabetic retinopathy or other retinal vascular diseases.
5. Intraocular foreign bodies: The removal of objects that have accidentally entered the eye.
6. Advanced cases of age-related macular degeneration (AMD) and other retinal disorders.

During vitreoretinal surgery, the surgeon makes small incisions in the eye to access the vitreous cavity and the retina. The vitreous humor is removed using specialized instruments, such as a vitrectomy cutter or forceps. Then, the surgeon can perform various procedures to address the underlying condition, like repairing retinal tears, removing scar tissue, or applying a gas or oil bubble to help reattach the retina. Finally, the eye is often filled with a saline solution, air, or a special type of gas or oil to maintain the proper shape and pressure inside the eye.

Vitreoretinal surgery requires advanced technical skills and expertise, as well as a thorough understanding of the anatomy and pathophysiology of the vitreous and retina. The primary goal of this procedure is to preserve or improve vision by addressing the underlying condition and preventing further damage to the delicate structures of the eye.

A Receiver Operating Characteristic (ROC) curve is a graphical representation used in medical decision-making and statistical analysis to illustrate the performance of a binary classifier system, such as a diagnostic test or a machine learning algorithm. It's a plot that shows the tradeoff between the true positive rate (sensitivity) and the false positive rate (1 - specificity) for different threshold settings.

The x-axis of an ROC curve represents the false positive rate (the proportion of negative cases incorrectly classified as positive), while the y-axis represents the true positive rate (the proportion of positive cases correctly classified as positive). Each point on the curve corresponds to a specific decision threshold, with higher points indicating better performance.

The area under the ROC curve (AUC) is a commonly used summary measure that reflects the overall performance of the classifier. An AUC value of 1 indicates perfect discrimination between positive and negative cases, while an AUC value of 0.5 suggests that the classifier performs no better than chance.

ROC curves are widely used in healthcare to evaluate diagnostic tests, predictive models, and screening tools for various medical conditions, helping clinicians make informed decisions about patient care based on the balance between sensitivity and specificity.

Fluorodeoxyglucose F18 (FDG-18) is not a medical condition, but a radiopharmaceutical used in medical imaging. It is a type of glucose (a simple sugar) that has been chemically combined with a small amount of a radioactive isotope called fluorine-18.

FDG-18 is used in positron emission tomography (PET) scans to help identify areas of the body where cells are using more energy than normal, such as cancerous tumors. The FDG-18 is injected into the patient's vein and travels throughout the body. Because cancer cells often use more glucose than normal cells, they tend to absorb more FDG-18.

Once inside the body, the FDG-18 emits positrons, which interact with electrons in nearby tissue, producing gamma rays that can be detected by a PET scanner. The resulting images can help doctors locate and assess the size and activity of cancerous tumors, as well as monitor the effectiveness of treatment.

Nonoxynol is a surfactant, or surface-active agent, that has been used in various medical and consumer products. It is a type of chemical compound known as a polyoxyethylene alkyl ether, which means it contains a hydrophilic (water-attracting) ethylene oxide group and a hydrophobic (water-repelling) alkyl group.

In the medical field, Nonoxynol has been used as a spermicide in various forms of birth control, such as creams, gels, films, and sponges. It works by disrupting the membrane of sperm cells, preventing them from fertilizing an egg. However, its use as a spermicide has declined due to concerns about its potential to cause irritation and inflammation in the genital area, which may increase the risk of sexually transmitted infections (STIs) and HIV transmission.

It's important to note that Nonoxynol is not currently recommended for use as a spermicide or microbicide due to its potential health risks. Always consult with a healthcare professional before using any medical product.

Treatment outcome is a term used to describe the result or effect of medical treatment on a patient's health status. It can be measured in various ways, such as through symptoms improvement, disease remission, reduced disability, improved quality of life, or survival rates. The treatment outcome helps healthcare providers evaluate the effectiveness of a particular treatment plan and make informed decisions about future care. It is also used in clinical research to compare the efficacy of different treatments and improve patient care.

Reference values, also known as reference ranges or reference intervals, are the set of values that are considered normal or typical for a particular population or group of people. These values are often used in laboratory tests to help interpret test results and determine whether a patient's value falls within the expected range.

The process of establishing reference values typically involves measuring a particular biomarker or parameter in a large, healthy population and then calculating the mean and standard deviation of the measurements. Based on these statistics, a range is established that includes a certain percentage of the population (often 95%) and excludes extreme outliers.

It's important to note that reference values can vary depending on factors such as age, sex, race, and other demographic characteristics. Therefore, it's essential to use reference values that are specific to the relevant population when interpreting laboratory test results. Additionally, reference values may change over time due to advances in measurement technology or changes in the population being studied.

Sirolimus is a medication that belongs to a class of drugs called immunosuppressants. It is also known as rapamycin. Sirolimus works by inhibiting the mammalian target of rapamycin (mTOR), which is a protein that plays a key role in cell growth and division.

Sirolimus is primarily used to prevent rejection of transplanted organs, such as kidneys, livers, and hearts. It works by suppressing the activity of the immune system, which can help to reduce the risk of the body rejecting the transplanted organ. Sirolimus is often used in combination with other immunosuppressive drugs, such as corticosteroids and calcineurin inhibitors.

Sirolimus is also being studied for its potential therapeutic benefits in a variety of other conditions, including cancer, tuberous sclerosis complex, and lymphangioleiomyomatosis. However, more research is needed to fully understand the safety and efficacy of sirolimus in these contexts.

It's important to note that sirolimus can have significant side effects, including increased risk of infections, mouth sores, high blood pressure, and kidney damage. Therefore, it should only be used under the close supervision of a healthcare provider.

Computer-Aided Design (CAD) is the use of computer systems to aid in the creation, modification, analysis, or optimization of a design. CAD software is used to create and manage designs in a variety of fields, such as architecture, engineering, and manufacturing. It allows designers to visualize their ideas in 2D or 3D, simulate how the design will function, and make changes quickly and easily. This can help to improve the efficiency and accuracy of the design process, and can also facilitate collaboration and communication among team members.

Papilledema is a medical term that refers to swelling of the optic nerve head, also known as the disc, which is the point where the optic nerve enters the back of the eye (the retina). This swelling can be caused by increased pressure within the skull, such as from brain tumors, meningitis, or idiopathic intracranial hypertension. Papilledema is usually detected through a routine eye examination and may be accompanied by symptoms such as headaches, visual disturbances, and nausea. If left untreated, papilledema can lead to permanent vision loss.

Keratoconus is a degenerative non-inflammatory disorder of the eye, primarily affecting the cornea. It is characterized by a progressive thinning and steepening of the central or paracentral cornea, causing it to assume a conical shape. This results in irregular astigmatism, myopia, and scattering of light leading to blurred vision, visual distortions, and sensitivity to glare. The exact cause of keratoconus is unknown, but it may be associated with genetics, eye rubbing, and certain medical conditions. It typically starts in the teenage years and progresses into the third or fourth decade of life. Treatment options include glasses, contact lenses, cross-linking, and corneal transplantation in advanced cases.

Laser In Situ Keratomileusis (LASIK) is a type of refractive surgery used to correct vision issues such as myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. The procedure involves reshaping the cornea, which is the clear, dome-shaped surface at the front of the eye, using an excimer laser.

In LASIK, a thin flap is created on the surface of the cornea using a femtosecond or microkeratome laser. The flap is then lifted, and the excimer laser is used to reshape the underlying tissue. After the reshaping is complete, the flap is replaced, allowing for quicker healing and visual recovery compared to other refractive surgery procedures.

LASIK is an outpatient procedure that typically takes about 30 minutes or less per eye. Most people can expect to see improved vision within a few days of the procedure, although it may take several weeks for vision to fully stabilize. LASIK has a high success rate and is generally considered safe when performed by a qualified surgeon. However, as with any surgical procedure, there are risks involved, including dry eye, infection, and visual complications such as glare or halos around lights.

X-ray computed tomography (CT) scanner is a medical imaging device that uses computer-processed combinations of many X-ray images taken from different angles to produce cross-sectional (tomographic) images (virtual "slices") of the body. These cross-sections can then be manipulated, through either additional computer processing or interactive viewing, to show various bodily structures and functions in 2D or 3D.

In contrast to conventional X-ray imaging, CT scanning provides detailed images of many types of tissue including lung, bone, soft tissue and blood vessels. CT is often used when rapid, detailed images are needed such as in trauma situations or for the detection and diagnosis of stroke, cancer, appendicitis, pulmonary embolism, and musculoskeletal disorders.

CT scanning is associated with some risks, particularly from exposure to ionizing radiation, which can lead to cancer and other diseases. However, the benefits of CT scanning, in particular its ability to detect life-threatening conditions early and accurately, generally outweigh the risks. As a result, it has become an important tool in modern medicine.

Computer-assisted signal processing is a medical term that refers to the use of computer algorithms and software to analyze, interpret, and extract meaningful information from biological signals. These signals can include physiological data such as electrocardiogram (ECG) waves, electromyography (EMG) signals, electroencephalography (EEG) readings, or medical images.

The goal of computer-assisted signal processing is to automate the analysis of these complex signals and extract relevant features that can be used for diagnostic, monitoring, or therapeutic purposes. This process typically involves several steps, including:

1. Signal acquisition: Collecting raw data from sensors or medical devices.
2. Preprocessing: Cleaning and filtering the data to remove noise and artifacts.
3. Feature extraction: Identifying and quantifying relevant features in the signal, such as peaks, troughs, or patterns.
4. Analysis: Applying statistical or machine learning algorithms to interpret the extracted features and make predictions about the underlying physiological state.
5. Visualization: Presenting the results in a clear and intuitive way for clinicians to review and use.

Computer-assisted signal processing has numerous applications in healthcare, including:

* Diagnosing and monitoring cardiac arrhythmias or other heart conditions using ECG signals.
* Assessing muscle activity and function using EMG signals.
* Monitoring brain activity and diagnosing neurological disorders using EEG readings.
* Analyzing medical images to detect abnormalities, such as tumors or fractures.

Overall, computer-assisted signal processing is a powerful tool for improving the accuracy and efficiency of medical diagnosis and monitoring, enabling clinicians to make more informed decisions about patient care.

Exudates and transudates are two types of bodily fluids that can accumulate in various body cavities or tissues as a result of injury, inflammation, or other medical conditions. Here are the medical definitions:

1. Exudates: These are fluids that accumulate due to an active inflammatory process. Exudates contain high levels of protein, white blood cells (such as neutrophils and macrophages), and sometimes other cells like red blood cells or cellular debris. They can be yellow, green, or brown in color and may have a foul odor due to the presence of dead cells and bacteria. Exudates are often seen in conditions such as abscesses, pneumonia, pleurisy, or wound infections.

Examples of exudative fluids include pus, purulent discharge, or inflammatory effusions.

2. Transudates: These are fluids that accumulate due to increased hydrostatic pressure or decreased oncotic pressure within the blood vessels. Transudates contain low levels of protein and cells compared to exudates. They are typically clear and pale yellow in color, with no odor. Transudates can be found in conditions such as congestive heart failure, liver cirrhosis, or nephrotic syndrome.

Examples of transudative fluids include ascites, pleural effusions, or pericardial effusions.

It is essential to differentiate between exudates and transudates because their underlying causes and treatment approaches may differ significantly. Medical professionals often use various tests, such as fluid analysis, to determine whether a fluid sample is an exudate or transudate.

A cross-sectional study is a type of observational research design that examines the relationship between variables at one point in time. It provides a snapshot or a "cross-section" of the population at a particular moment, allowing researchers to estimate the prevalence of a disease or condition and identify potential risk factors or associations.

In a cross-sectional study, data is collected from a sample of participants at a single time point, and the variables of interest are measured simultaneously. This design can be used to investigate the association between exposure and outcome, but it cannot establish causality because it does not follow changes over time.

Cross-sectional studies can be conducted using various data collection methods, such as surveys, interviews, or medical examinations. They are often used in epidemiology to estimate the prevalence of a disease or condition in a population and to identify potential risk factors that may contribute to its development. However, because cross-sectional studies only provide a snapshot of the population at one point in time, they cannot account for changes over time or determine whether exposure preceded the outcome.

Therefore, while cross-sectional studies can be useful for generating hypotheses and identifying potential associations between variables, further research using other study designs, such as cohort or case-control studies, is necessary to establish causality and confirm any findings.

The Bruch membrane is a thin, layered structure that separates the retina from the choroid in the eye. It is composed of five layers: the basement membrane of the retinal pigment epithelium (RPE), the inner collagenous layer, the elastic layer, the outer collagenous layer, and the basement membrane of the choriocapillaris. The Bruch membrane provides structural support to the RPE and serves as a barrier between the retina and the choroid, allowing for the selective transport of nutrients and waste products. It also plays a role in maintaining the health of the photoreceptors in the retina. Damage to the Bruch membrane is associated with age-related macular degeneration (AMD), a leading cause of vision loss in older adults.

Photoacoustic techniques, also known as optoacoustic techniques, refer to a group of diagnostic methods used in medicine and biology that combine the principles of laser-induced ultrasound and optical absorption contrast. These techniques involve illuminating a sample or tissue with a short laser pulse, which is absorbed by chromophores (light-absorbing molecules) within the tissue. The absorption of light energy leads to thermoelastic expansion and generates broadband acoustic waves, which are then detected using ultrasound transducers.

The resulting photoacoustic signals can provide information about the optical absorption properties, concentration, and distribution of chromophores in the tissue, such as hemoglobin, melanin, or exogenous contrast agents. Photoacoustic techniques have several advantages over traditional optical imaging methods, including deeper penetration depths (up to a few centimeters) and higher spatial resolution (down to a few micrometers).

There are various photoacoustic techniques, including photoacoustic microscopy (PAM), photoacoustic tomography (PAT), and functional photoacoustic imaging. These methods have shown great potential in various biomedical applications, such as cancer detection, blood oxygenation mapping, skin melanoma characterization, and brain function monitoring.

Phacoemulsification is a surgical procedure used in cataract removal. It involves using an ultrasonic device to emulsify (break up) the cloudy lens (cataract) into small pieces, which are then aspirated or sucked out through a small incision. This procedure allows for smaller incisions and faster recovery times compared to traditional cataract surgery methods. After the cataract is removed, an artificial intraocular lens (IOL) is typically implanted to replace the natural lens and restore vision.

Radiation scattering is a physical process in which radiation particles or waves deviate from their original direction due to interaction with matter. This phenomenon can occur through various mechanisms such as:

1. Elastic Scattering: Also known as Thomson scattering or Rayleigh scattering, it occurs when the energy of the scattered particle or wave remains unchanged after the collision. In the case of electromagnetic radiation (e.g., light), this results in a change of direction without any loss of energy.
2. Inelastic Scattering: This type of scattering involves an exchange of energy between the scattered particle and the target medium, leading to a change in both direction and energy of the scattered particle or wave. An example is Compton scattering, where high-energy photons (e.g., X-rays or gamma rays) interact with charged particles (usually electrons), resulting in a decrease in photon energy and an increase in electron kinetic energy.
3. Coherent Scattering: In this process, the scattered radiation maintains its phase relationship with the incident radiation, leading to constructive and destructive interference patterns. An example is Bragg scattering, which occurs when X-rays interact with a crystal lattice, resulting in diffraction patterns that reveal information about the crystal structure.

In medical contexts, radiation scattering can have both beneficial and harmful effects. For instance, in diagnostic imaging techniques like computed tomography (CT) scans, radiation scattering contributes to image noise and reduces contrast resolution. However, in radiation therapy for cancer treatment, controlled scattering of therapeutic radiation beams can help ensure that the tumor receives a uniform dose while minimizing exposure to healthy tissues.

Vitelliform Macular Dystrophy is a genetic eye condition that affects the macula, which is the central part of the retina responsible for sharp, detailed vision. This disorder is characterized by the formation of yellowish deposits or lesions beneath the retina at the macula, giving it an appearance similar to an egg yolk (hence the name "vitelliform"). These deposits can disturb vision and may lead to progressive vision loss over time.

There are different types of Vitelliform Macular Dystrophy, with the most common being Best's Disease or Vitelliform Macular Dystrophy type 1 (VMD1). This form is caused by mutations in the BEST1 gene and typically manifests in childhood or early adulthood. The condition can progress through various stages, including the appearance of a yellowish lesion, followed by atrophy and scarring of the retina, which can result in significant vision loss.

Another form is Vitelliform Macular Dystrophy type 2 (VMD2), caused by mutations in the PRPH2 gene. This condition tends to progress more slowly than VMD1 and may not lead to severe vision loss.

Early diagnosis, monitoring, and low-vision rehabilitation can help manage the symptoms of Vitelliform Macular Dystrophy and maintain visual function as much as possible.

Retrograde degeneration is a medical term that refers to the process of degeneration or damage in neurons (nerve cells) that occurs backward from the site of injury or disease along the axon, which is the part of the neuron that transmits electrical signals to other neurons. This can lead to functional loss and may eventually result in the death of the neuron. Retrograde degeneration is often seen in neurodegenerative disorders such as Amyotrophic Lateral Sclerosis (ALS) and Alzheimer's disease, as well as in spinal cord injuries.

The Bowman membrane, also known as the Bowman's capsule, is a part of the nephron in the kidney. It is the outermost layer of the renal corpuscle and surrounds the glomerulus. The primary function of the Bowman membrane is to filter blood and produce urine.

The Bowman membrane is composed of two layers: an inner visceral layer, which is closely applied to the glomerular capillaries, and an outer parietal layer, which forms the inner lining of the Bowman's capsule. The space between these two layers is called the urinary space or Bowman's space.

The filtration process in the Bowman membrane allows for the passage of small molecules such as water, glucose, and amino acids from the blood into the urinary space, while larger molecules like proteins and blood cells are retained in the bloodstream. The fluid that passes through the Bowman membrane then flows into the tubular part of the nephron, where it is further modified before being excreted as urine.

A stent is a small mesh tube that's used to treat narrow or weak arteries. Arteries are blood vessels that carry blood away from your heart to other parts of your body. A stent is placed in an artery as part of a procedure called angioplasty. Angioplasty restores blood flow through narrowed or blocked arteries by inflating a tiny balloon inside the blocked artery to widen it.

The stent is then inserted into the widened artery to keep it open. The stent is usually made of metal, but some are coated with medication that is slowly and continuously released to help prevent the formation of scar tissue in the artery. This can reduce the chance of the artery narrowing again.

Stents are also used in other parts of the body, such as the neck (carotid artery) and kidneys (renal artery), to help maintain blood flow and prevent blockages. They can also be used in the urinary system to treat conditions like ureteropelvic junction obstruction or narrowing of the urethra.

Cardiovascular agents are a class of medications that are used to treat various conditions related to the cardiovascular system, which includes the heart and blood vessels. These agents can be further divided into several subcategories based on their specific mechanisms of action and therapeutic effects. Here are some examples:

1. Antiarrhythmics: These drugs are used to treat abnormal heart rhythms or arrhythmias. They work by stabilizing the electrical activity of the heart and preventing irregular impulses from spreading through the heart muscle.
2. Antihypertensives: These medications are used to lower high blood pressure, also known as hypertension. There are several classes of antihypertensive drugs, including diuretics, beta-blockers, calcium channel blockers, and angiotensin-converting enzyme (ACE) inhibitors.
3. Anticoagulants: These drugs are used to prevent blood clots from forming or growing larger. They work by interfering with the coagulation cascade, which is a series of chemical reactions that lead to the formation of a blood clot.
4. Antiplatelet agents: These medications are used to prevent platelets in the blood from sticking together and forming clots. They work by inhibiting the aggregation of platelets, which are small cells in the blood that help form clots.
5. Lipid-lowering agents: These drugs are used to lower cholesterol and other fats in the blood. They work by reducing the production or absorption of cholesterol in the body or increasing the removal of cholesterol from the bloodstream. Examples include statins, bile acid sequestrants, and PCSK9 inhibitors.
6. Vasodilators: These medications are used to widen blood vessels and improve blood flow. They work by relaxing the smooth muscle in the walls of blood vessels, causing them to dilate or widen. Examples include nitrates, calcium channel blockers, and ACE inhibitors.
7. Inotropes: These drugs are used to increase the force of heart contractions. They work by increasing the sensitivity of heart muscle cells to calcium ions, which are necessary for muscle contraction.

These are just a few examples of cardiovascular medications that are used to treat various conditions related to the heart and blood vessels. It is important to note that these medications can have side effects and should be taken under the guidance of a healthcare provider.

Coronary thrombosis is a medical condition that refers to the formation of a blood clot (thrombus) inside a coronary artery, which supplies oxygenated blood to the heart muscle. The development of a thrombus can partially or completely obstruct blood flow, leading to insufficient oxygen supply to the heart muscle. This can cause chest pain (angina) or a heart attack (myocardial infarction), depending on the severity and duration of the blockage.

Coronary thrombosis often results from the rupture of an atherosclerotic plaque, a buildup of cholesterol, fat, calcium, and other substances in the inner lining (endothelium) of the coronary artery. The ruptured plaque exposes the underlying tissue to the bloodstream, triggering the coagulation cascade and resulting in the formation of a thrombus.

Immediate medical attention is crucial for managing coronary thrombosis, as timely treatment can help restore blood flow, prevent further damage to the heart muscle, and reduce the risk of complications such as heart failure or life-threatening arrhythmias. Treatment options may include medications, such as antiplatelet agents, anticoagulants, and thrombolytic drugs, or interventional procedures like angioplasty and stenting to open the blocked artery. In some cases, surgical intervention, such as coronary artery bypass grafting (CABG), may be necessary.

In medical terms, "tears" are a clear, salty liquid that is produced by the tear glands (lacrimal glands) in our eyes. They serve to keep the eyes moist, protect against dust and other foreign particles, and help to provide clear vision by maintaining a smooth surface on the front of the eye. Tears consist of water, oil, and mucus, which help to prevent evaporation and ensure that the tears spread evenly across the surface of the eye. Emotional or reflexive responses, such as crying or yawning, can also stimulate the production of tears.

A scotoma is a blind spot or area of reduced vision within the visual field. It's often surrounded by an area of less distinct vision and can be caused by various conditions such as eye diseases, neurological disorders, or brain injuries. A scotoma may be temporary or permanent, depending on its underlying cause.

There are different types of scotomas, including:

1. Central scotoma - a blind spot in the center of the visual field, often associated with conditions like age-related macular degeneration and diabetic retinopathy.
2. Paracentral scotoma - a blind spot located slightly away from the center of the visual field, which can be caused by optic neuritis or other optic nerve disorders.
3. Peripheral scotoma - a blind spot in the peripheral vision, often associated with retinal diseases like retinitis pigmentosa.
4. Absolute scotoma - a complete loss of vision in a specific area of the visual field.
5. Relative scotoma - a partial loss of vision in which some details can still be perceived, but not as clearly or vividly as in normal vision.

It is essential to consult an eye care professional if you experience any changes in your vision or notice a scotoma, as early detection and treatment can help prevent further vision loss.

Corneal surgery, laser refers to a type of surgical procedure performed on the cornea (the clear, dome-shaped surface at the front of the eye) using a laser. The most common type of laser used in corneal surgery is an excimer laser, which can be used to reshape the cornea and correct refractive errors such as nearsightedness, farsightedness, and astigmatism. This procedure is commonly known as LASIK (Laser-Assisted In Situ Keratomileusis).

Another type of laser corneal surgery is PRK (Photorefractive Keratectomy) which uses a laser to reshape the surface of the cornea. This procedure is typically used for patients who have thin corneas or other conditions that make them ineligible for LASIK.

Additionally, there are other types of laser corneal surgeries such as LASEK (Laser Epithelial Keratomileusis), Epi-LASIK (Epithelial Laser-Assisted Keratomileusis) and SBK (Sub Bowman's Keratomileusis) which are variations of the above procedures.

It is important to note that, as with any surgical procedure, laser corneal surgery has risks and potential complications, including dry eye, infection, and visual symptoms such as glare or halos around lights. It is essential for patients to have a thorough examination and consultation with an ophthalmologist before deciding if laser corneal surgery is the right choice for them.

Microradiography is a radiographic technique that uses X-rays to produce detailed images of small specimens, such as microscopic slides or individual cells. In this process, the specimen is placed in close contact with a high-resolution photographic emulsion, and then exposed to X-rays. The resulting image shows the distribution of radiopaque materials within the specimen, providing information about its internal structure and composition at a microscopic level.

Microradiography can be used for various applications in medical research and diagnosis, including the study of bone and tooth microstructure, the analysis of tissue pathology, and the examination of mineralized tissues such as calcifications or osteogenic lesions. The technique offers high resolution and contrast, making it a valuable tool for researchers and clinicians seeking to understand the complex structures and processes that occur at the microscopic level in living organisms.

Tooth demineralization is a process that involves the loss of minerals, such as calcium and phosphate, from the hard tissues of the teeth. This process can lead to the development of dental caries or tooth decay. Demineralization occurs when acids produced by bacteria in the mouth attack the enamel of the tooth, dissolving its mineral content. Over time, these attacks can create holes or cavities in the teeth. Fluoride, found in many toothpastes and public water supplies, can help to remineralize teeth and prevent decay. Good oral hygiene practices, such as brushing and flossing regularly, can also help to prevent demineralization by removing plaque and bacteria from the mouth.

Hydrophilic contact lenses are a type of contact lens that is designed to absorb and retain water. These lenses are made from materials that have an affinity for water, which helps them to remain moist and comfortable on the eye. The water content of hydrophilic contact lenses can vary, but typically ranges from 30-80% by weight.

Hydrophilic contact lenses are often used to correct refractive errors such as myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. They can be made in a variety of materials, including soft hydrogel and silicone hydrogel.

One advantage of hydrophilic contact lenses is that they tend to be more comfortable to wear than other types of contacts, as they retain moisture and conform closely to the shape of the eye. However, they may also be more prone to deposits and buildup, which can lead to protein accumulation and discomfort over time. Proper care and cleaning are essential to maintain the health of the eyes when wearing hydrophilic contact lenses.

Coronary restenosis is the re-narrowing or re-occlusion of a coronary artery after a previous successful procedure to open or widen the artery, such as angioplasty or stenting. This narrowing is usually caused by the excessive growth of scar tissue or smooth muscle cells in the artery lining, which can occur spontaneously or as a response to the initial procedure. Restenosis can lead to recurrent symptoms of coronary artery disease, such as chest pain or shortness of breath, and may require additional medical intervention.

Ophthalmologic surgical procedures refer to various types of surgeries performed on the eye and its surrounding structures by trained medical professionals called ophthalmologists. These procedures aim to correct or improve vision, diagnose and treat eye diseases or injuries, and enhance the overall health and functionality of the eye. Some common examples of ophthalmologic surgical procedures include:

1. Cataract Surgery: This procedure involves removing a cloudy lens (cataract) from the eye and replacing it with an artificial intraocular lens (IOL).
2. LASIK (Laser-Assisted In Situ Keratomileusis): A type of refractive surgery that uses a laser to reshape the cornea, correcting nearsightedness, farsightedness, and astigmatism.
3. Glaucoma Surgery: Several surgical options are available for treating glaucoma, including laser trabeculoplasty, traditional trabeculectomy, and various drainage device implantations. These procedures aim to reduce intraocular pressure (IOP) and prevent further optic nerve damage.
4. Corneal Transplant: This procedure involves replacing a damaged or diseased cornea with a healthy donor cornea to restore vision and improve the eye's appearance.
5. Vitreoretinal Surgery: These procedures focus on treating issues within the vitreous humor (gel-like substance filling the eye) and the retina, such as retinal detachment, macular holes, or diabetic retinopathy.
6. Strabismus Surgery: This procedure aims to correct misalignment of the eyes (strabismus) by adjusting the muscles responsible for eye movement.
7. Oculoplastic Surgery: These procedures involve reconstructive, cosmetic, and functional surgeries around the eye, such as eyelid repair, removal of tumors, or orbital fracture repairs.
8. Pediatric Ophthalmologic Procedures: Various surgical interventions are performed on children to treat conditions like congenital cataracts, amblyopia (lazy eye), or blocked tear ducts.

These are just a few examples of ophthalmic surgical procedures. The specific treatment plan will depend on the individual's condition and overall health.

An esophagogastroduodenoscope, often referred to as an "esophagogastroscopy" or simply "esophagoscope," is a medical device used for visual examination of the upper digestive tract, including the esophagus, stomach, and duodenum. It is a long, flexible tube with a light and camera at the end, which allows doctors to see detailed images of the inside of these organs and diagnose various conditions such as gastroesophageal reflux disease (GERD), ulcers, and cancer. The procedure of using an esophagogastroduodenoscope is called an "esophagogastroduodenoscopy" or "EGD."

Dental caries activity tests are a group of diagnostic procedures used to measure or evaluate the activity and progression of dental caries (tooth decay). These tests help dentists and dental professionals determine the most appropriate treatment plan for their patients. Here are some commonly used dental caries activity tests:

1. **Bacterial Counts:** This test measures the number of bacteria present in a sample taken from the tooth surface. A higher bacterial count indicates a higher risk of dental caries.
2. **Sucrose Challenge Test:** In this test, a small amount of sucrose (table sugar) is applied to the tooth surface. After a set period, the presence and quantity of acid produced by bacteria are measured. Increased acid production suggests a higher risk of dental caries.
3. **pH Monitoring:** This test measures the acidity or alkalinity (pH level) of the saliva or plaque in the mouth. A lower pH level indicates increased acidity, which can lead to tooth decay.
4. **Dye Tests:** These tests use a special dye that stains active carious lesions on the tooth surface. The stained areas are then easily visible and can be evaluated for treatment.
5. **Transillumination Test:** A bright light is shone through the tooth to reveal any cracks, fractures, or areas of decay. This test helps identify early stages of dental caries that may not yet be visible during a routine dental examination.
6. **Laser Fluorescence Tests:** These tests use a handheld device that emits a laser beam to detect and quantify the presence of bacterial biofilm or dental plaque on the tooth surface. Increased fluorescence suggests a higher risk of dental caries.

It is important to note that these tests should be used as part of a comprehensive dental examination and not as standalone diagnostic tools. A dentist's clinical judgment, in conjunction with these tests, will help determine the best course of treatment for each individual patient.

Coronary stenosis is a medical condition that refers to the narrowing of the coronary arteries, which supply oxygen-rich blood to the heart muscle. This narrowing is typically caused by the buildup of plaque, made up of fat, cholesterol, and other substances, on the inner walls of the arteries. Over time, as the plaque hardens and calcifies, it can cause the artery to become narrowed or blocked, reducing blood flow to the heart muscle.

Coronary stenosis can lead to various symptoms and complications, including chest pain (angina), shortness of breath, irregular heart rhythms (arrhythmias), and heart attacks. Treatment options for coronary stenosis may include lifestyle changes, medications, medical procedures such as angioplasty or bypass surgery, or a combination of these approaches. Regular check-ups and diagnostic tests, such as stress testing or coronary angiography, can help detect and monitor coronary stenosis over time.

Coronary balloon angioplasty is a minimally invasive medical procedure used to widen narrowed or obstructed coronary arteries (the blood vessels that supply oxygen-rich blood to the heart muscle) and improve blood flow to the heart. This procedure is typically performed in conjunction with the insertion of a stent, a small mesh tube that helps keep the artery open.

During coronary balloon angioplasty, a thin, flexible catheter with a deflated balloon at its tip is inserted into a blood vessel, usually through a small incision in the groin or arm. The catheter is then guided to the narrowed or obstructed section of the coronary artery. Once in position, the balloon is inflated to compress the plaque against the artery wall and widen the lumen (the inner space) of the artery. This helps restore blood flow to the heart muscle.

The procedure is typically performed under local anesthesia and conscious sedation to minimize discomfort. Coronary balloon angioplasty is a relatively safe and effective treatment for many people with coronary artery disease, although complications such as bleeding, infection, or re-narrowing of the artery (restenosis) can occur in some cases.

The Descemet membrane is the thin, transparent basement membrane that is produced by the corneal endothelial cells. It is located between the corneal stroma and the corneal endothelium, which is the innermost layer of the cornea. The Descemet membrane provides structural support for the corneal endothelium and helps to maintain the proper hydration and clarity of the cornea. It is named after the French physician Jean Descemet, who first described it in 1752.

I'm sorry for any confusion, but "pilot projects" is not a medical term per se. Instead, it is a general term used in various fields, including healthcare and medicine, to describe a small-scale initiative that is implemented on a temporary basis to evaluate its feasibility, effectiveness, or impact before deciding whether to expand or continue it.

In the context of healthcare, pilot projects might involve testing new treatment protocols, implementing innovative care models, or introducing technology solutions in a limited setting to assess their potential benefits and drawbacks. The results of these projects can help inform decisions about broader implementation and provide valuable insights for improving the quality and efficiency of healthcare services.

A Severity of Illness Index is a measurement tool used in healthcare to assess the severity of a patient's condition and the risk of mortality or other adverse outcomes. These indices typically take into account various physiological and clinical variables, such as vital signs, laboratory values, and co-morbidities, to generate a score that reflects the patient's overall illness severity.

Examples of Severity of Illness Indices include the Acute Physiology and Chronic Health Evaluation (APACHE) system, the Simplified Acute Physiology Score (SAPS), and the Mortality Probability Model (MPM). These indices are often used in critical care settings to guide clinical decision-making, inform prognosis, and compare outcomes across different patient populations.

It is important to note that while these indices can provide valuable information about a patient's condition, they should not be used as the sole basis for clinical decision-making. Rather, they should be considered in conjunction with other factors, such as the patient's overall clinical presentation, treatment preferences, and goals of care.

Low tension glaucoma, also known as normal tension glaucoma, is a type of glaucoma characterized by optic nerve damage and visual field loss in the absence of consistently elevated intraocular pressure (IOP). In this form of glaucoma, the IOP typically remains within the statistically normal range, which is generally defined as below 21 mmHg. However, some individuals may have an IOP that is considered "low tension" for their specific optic nerve susceptibility.

The exact cause of low tension glaucoma remains unclear, but it is thought to involve factors such as impaired blood flow to the optic nerve, genetic predisposition, and sensitivity to minor fluctuations in IOP. People with low tension glaucoma may require close monitoring and management, including regular IOP checks, visual field testing, and sometimes the use of medications or surgical interventions to reduce the risk of further optic nerve damage and vision loss.

Medical Definition:

Magnetic Resonance Imaging (MRI) is a non-invasive diagnostic imaging technique that uses a strong magnetic field and radio waves to create detailed cross-sectional or three-dimensional images of the internal structures of the body. The patient lies within a large, cylindrical magnet, and the scanner detects changes in the direction of the magnetic field caused by protons in the body. These changes are then converted into detailed images that help medical professionals to diagnose and monitor various medical conditions, such as tumors, injuries, or diseases affecting the brain, spinal cord, heart, blood vessels, joints, and other internal organs. MRI does not use radiation like computed tomography (CT) scans.

Prosthesis design is a specialized field in medical device technology that involves creating and developing artificial substitutes to replace a missing body part, such as a limb, tooth, eye, or internal organ. The design process typically includes several stages: assessment of the patient's needs, selection of appropriate materials, creation of a prototype, testing and refinement, and final fabrication and fitting of the prosthesis.

The goal of prosthesis design is to create a device that functions as closely as possible to the natural body part it replaces, while also being comfortable, durable, and aesthetically pleasing for the patient. The design process may involve collaboration between medical professionals, engineers, and designers, and may take into account factors such as the patient's age, lifestyle, occupation, and overall health.

Prosthesis design can be highly complex, particularly for advanced devices such as robotic limbs or implantable organs. These devices often require sophisticated sensors, actuators, and control systems to mimic the natural functions of the body part they replace. As a result, prosthesis design is an active area of research and development in the medical field, with ongoing efforts to improve the functionality, comfort, and affordability of these devices for patients.

Retinal telangiectasia is a medical condition characterized by the dilation and tortuosity (abnormal twisting or turning) of small retinal blood vessels, specifically the capillaries in the back part of the eye called the retina. This condition can be idiopathic (without a known cause), or it can be associated with various systemic diseases or genetic syndromes.

Retinal telangiectasia is often accompanied by other retinal abnormalities, such as microaneurysms, exudates, and hemorrhages. In some cases, it may lead to vision loss due to macular edema (fluid accumulation in the central part of the retina) or retinal detachment.

There are two main types of retinal telangiectasia:

1. Eales' disease: This is a rare idiopathic condition that primarily affects young adults, particularly males from Asian and Middle Eastern countries. It typically presents with retinal telangiectasia in the peripheral retina, along with inflammation, vitreous hemorrhage, and neovascularization (the growth of new blood vessels).
2. Coats' disease: This is a congenital or infantile disorder that affects the retinal vasculature. It primarily affects males and is characterized by unilateral retinal telangiectasia, exudates, and sometimes retinal detachment. Coats' disease can lead to severe vision loss if not treated promptly.

It is essential to monitor and manage retinal telangiectasia to prevent or treat associated complications and preserve vision. Treatment options may include laser photocoagulation, cryotherapy, intravitreal injections of anti-VEGF (vascular endothelial growth factor) drugs, or vitrectomy surgery, depending on the severity and progression of the condition.

Ischemic optic neuropathy (ION) is a medical condition that refers to the damage or death of the optic nerve due to insufficient blood supply. The optic nerve is responsible for transmitting visual information from the eye to the brain.

In ION, the blood vessels that supply the optic nerve become blocked or narrowed, leading to decreased blood flow and oxygen delivery to the nerve fibers. This results in inflammation, swelling, and ultimately, damage to the optic nerve. The damage can cause sudden, painless vision loss, often noticed upon waking up in the morning.

There are two types of ION: anterior ischemic optic neuropathy (AION) and posterior ischemic optic neuropathy (PION). AION affects the front part of the optic nerve, while PION affects the back part of the nerve. AION is further classified into arteritic and non-arteritic types, depending on whether it is caused by giant cell arteritis or not.

Risk factors for ION include age (most commonly occurring in people over 50), hypertension, diabetes, smoking, sleep apnea, and other cardiovascular diseases. Treatment options depend on the type and cause of ION and may include controlling underlying medical conditions, administering corticosteroids, or undergoing surgical procedures to improve blood flow.

Angioscopy is a medical diagnostic procedure that uses a small fiber-optic scope, called an angioscope, to directly visualize the interior of blood vessels. The angioscope is inserted into the vessel through a small incision or catheter and allows physicians to examine the vessel walls for abnormalities such as plaque buildup, inflammation, or damage. This procedure can be used to diagnose and monitor conditions such as coronary artery disease, peripheral artery disease, and vasculitis. It can also be used during surgical procedures to assist with the placement of stents or other devices in the blood vessels.

An injection is a medical procedure in which a medication, vaccine, or other substance is introduced into the body using a needle and syringe. The substance can be delivered into various parts of the body, including into a vein (intravenous), muscle (intramuscular), under the skin (subcutaneous), or into the spinal canal (intrathecal or spinal).

Injections are commonly used to administer medications that cannot be taken orally, have poor oral bioavailability, need to reach the site of action quickly, or require direct delivery to a specific organ or tissue. They can also be used for diagnostic purposes, such as drawing blood samples (venipuncture) or injecting contrast agents for imaging studies.

Proper technique and sterile conditions are essential when administering injections to prevent infection, pain, and other complications. The choice of injection site depends on the type and volume of the substance being administered, as well as the patient's age, health status, and personal preferences.

Infrared rays are not typically considered in the context of medical definitions. They are a type of electromagnetic radiation with longer wavelengths than those of visible light, ranging from 700 nanometers to 1 millimeter. In the field of medicine, infrared radiation is sometimes used in therapeutic settings for its heat properties, such as in infrared saunas or infrared therapy devices. However, infrared rays themselves are not a medical condition or diagnosis.

Contrast media are substances that are administered to a patient in order to improve the visibility of internal body structures or processes in medical imaging techniques such as X-rays, CT scans, MRI scans, and ultrasounds. These media can be introduced into the body through various routes, including oral, rectal, or intravenous administration.

Contrast media work by altering the appearance of bodily structures in imaging studies. For example, when a patient undergoes an X-ray examination, contrast media can be used to highlight specific organs, tissues, or blood vessels, making them more visible on the resulting images. In CT and MRI scans, contrast media can help to enhance the differences between normal and abnormal tissues, allowing for more accurate diagnosis and treatment planning.

There are several types of contrast media available, each with its own specific properties and uses. Some common examples include barium sulfate, which is used as a contrast medium in X-ray studies of the gastrointestinal tract, and iodinated contrast media, which are commonly used in CT scans to highlight blood vessels and other structures.

While contrast media are generally considered safe, they can sometimes cause adverse reactions, ranging from mild symptoms such as nausea or hives to more serious complications such as anaphylaxis or kidney damage. As a result, it is important for healthcare providers to carefully evaluate each patient's medical history and individual risk factors before administering contrast media.

Spontaneous rupture in medical terms refers to the sudden breaking or tearing of an organ, tissue, or structure within the body without any identifiable trauma or injury. This event can occur due to various reasons such as weakening of the tissue over time because of disease or degeneration, or excessive pressure on the tissue.

For instance, a spontaneous rupture of the appendix is called an "appendiceal rupture," which can lead to peritonitis, a serious inflammation of the abdominal cavity. Similarly, a spontaneous rupture of a blood vessel, like an aortic aneurysm, can result in life-threatening internal bleeding.

Spontaneous ruptures are often medical emergencies and require immediate medical attention for proper diagnosis and treatment.

Angiogenesis inhibitors are a class of drugs that block the growth of new blood vessels (angiogenesis). They work by targeting specific molecules involved in the process of angiogenesis, such as vascular endothelial growth factor (VEGF) and its receptors. By blocking these molecules, angiogenesis inhibitors can prevent the development of new blood vessels that feed tumors, thereby slowing or stopping their growth.

Angiogenesis inhibitors are used in the treatment of various types of cancer, including colon, lung, breast, kidney, and ovarian cancer. They may be given alone or in combination with other cancer treatments, such as chemotherapy or radiation therapy. Some examples of angiogenesis inhibitors include bevacizumab (Avastin), sorafenib (Nexavar), sunitinib (Sutent), and pazopanib (Votrient).

It's important to note that while angiogenesis inhibitors can be effective in treating cancer, they can also have serious side effects, such as high blood pressure, bleeding, and damage to the heart or kidneys. Therefore, it's essential that patients receive careful monitoring and management of these potential side effects while undergoing treatment with angiogenesis inhibitors.

Signal-to-Noise Ratio (SNR) is not a medical term per se, but it is widely used in various medical fields, particularly in diagnostic imaging and telemedicine. It is a measure from signal processing that compares the level of a desired signal to the level of background noise.

In the context of medical imaging (like MRI, CT scans, or ultrasound), a higher SNR means that the useful information (the signal) is stronger relative to the irrelevant and distracting data (the noise). This results in clearer, more detailed, and more accurate images, which can significantly improve diagnostic precision.

In telemedicine and remote patient monitoring, SNR is crucial for ensuring high-quality audio and video communication between healthcare providers and patients. A good SNR ensures that the transmitted data (voice or image) is received with minimal interference or distortion, enabling effective virtual consultations and diagnoses.

Retinal cone photoreceptor cells are specialized neurons located in the retina of the eye, responsible for visual phototransduction and color vision. They are one of the two types of photoreceptors, with the other being rods, which are more sensitive to low light levels. Cones are primarily responsible for high-acuity, color vision during daylight or bright-light conditions.

There are three types of cone cells, each containing different photopigments that absorb light at distinct wavelengths: short (S), medium (M), and long (L) wavelengths, which correspond to blue, green, and red light, respectively. The combination of signals from these three types of cones allows the human visual system to perceive a wide range of colors and discriminate between them. Cones are densely packed in the central region of the retina, known as the fovea, which provides the highest visual acuity.

The optic chiasm is a structure in the brain where the optic nerves from each eye meet and cross. This allows for the integration of visual information from both eyes into the brain's visual cortex, creating a single, combined image of the visual world. The optic chiasm plays an important role in the processing of visual information and helps to facilitate depth perception and other complex visual tasks. Damage to the optic chiasm can result in various visual field deficits, such as bitemporal hemianopsia, where there is a loss of vision in the outer halves (temporal fields) of both eyes' visual fields.

A pupil, in medical terms, refers to the circular opening in the center of the iris (the colored part of the eye) that allows light to enter and reach the retina. The size of the pupil can change involuntarily in response to light intensity and emotional state, as well as voluntarily through certain eye exercises or with the use of eye drops. Pupillary reactions are important in clinical examinations as they can provide valuable information about the nervous system's functioning, particularly the brainstem and cranial nerves II and III.

A prolapse is a medical condition where an organ or tissue in the body slips from its normal position and drops down into a lower part of the body. This usually occurs when the muscles and ligaments that support the organ become weak or stretched. The most common types of prolapses include:

* Uterine prolapse: When the uterus slips down into or protrudes out of the vagina.
* Rectal prolapse: When the rectum (the lower end of the colon) slips outside the anus.
* Bladder prolapse (cystocele): When the bladder drops into the vagina.
* Small bowel prolapse (enterocele): When the small intestine bulges into the vagina.

Prolapses can cause various symptoms, such as discomfort, pain, pressure, and difficulty with urination or bowel movements. Treatment options depend on the severity of the prolapse and may include lifestyle changes, physical therapy, medication, or surgery.

In the context of medical terminology, "light" doesn't have a specific or standardized definition on its own. However, it can be used in various medical terms and phrases. For example, it could refer to:

1. Visible light: The range of electromagnetic radiation that can be detected by the human eye, typically between wavelengths of 400-700 nanometers. This is relevant in fields such as ophthalmology and optometry.
2. Therapeutic use of light: In some therapies, light is used to treat certain conditions. An example is phototherapy, which uses various wavelengths of ultraviolet (UV) or visible light for conditions like newborn jaundice, skin disorders, or seasonal affective disorder.
3. Light anesthesia: A state of reduced consciousness in which the patient remains responsive to verbal commands and physical stimulation. This is different from general anesthesia where the patient is completely unconscious.
4. Pain relief using light: Certain devices like transcutaneous electrical nerve stimulation (TENS) units have a 'light' setting, indicating lower intensity or frequency of electrical impulses used for pain management.

Without more context, it's hard to provide a precise medical definition of 'light'.

Telangiectasia is a medical term that refers to the dilation and widening of small blood vessels called capillaries, leading to their visibility under the skin or mucous membranes. These dilated vessels often appear as tiny red lines or patterns, measuring less than 1 millimeter in diameter.

Telangiectasias can occur in various parts of the body, such as the face, nose, cheeks, legs, and fingers. They are typically harmless but may cause cosmetic concerns for some individuals. In certain cases, telangiectasias can be a sign of an underlying medical condition, like rosacea, hereditary hemorrhagic telangiectasia (HHT), or liver disease.

It is essential to consult with a healthcare professional if you notice any unusual changes in your skin or mucous membranes, as they can provide appropriate evaluation and treatment recommendations based on the underlying cause of the telangiectasias.

Percutaneous Coronary Intervention (PCI), also known as coronary angioplasty, is a non-surgical procedure that opens up clogged coronary arteries to improve blood flow to the heart. It involves inserting a thin, flexible catheter into an artery in the groin or wrist and guiding it to the blocked artery in the heart. A small balloon is then inflated to widen the narrowed or blocked artery, and sometimes a stent (a tiny mesh tube) is placed to keep the artery open. This procedure helps to restore and maintain blood flow to the heart muscle, reducing symptoms of angina and improving overall cardiac function.

Spermatocidal agents are substances or chemicals that have the ability to destroy or inhibit sperm cells, making them non-functional. These agents are often used in spermicides, which are a type of contraceptive method. Spermicides work by physically blocking the cervix and killing any sperm that come into contact with the spermicidal agent. Common spermatocidal agents include Nonoxynol-9, Benzalkonium chloride, and Chlorhexidine gluconate. It's important to note that while spermicides can provide some protection against pregnancy, they are not considered a highly effective form of birth control when used alone.

Hereditary eye diseases refer to conditions that affect the eyes and are passed down from parents to their offspring through genetics. These diseases are caused by mutations or changes in an individual's DNA that are inherited from their parents. The mutations can occur in any of the genes associated with eye development, function, or health.

There are many different types of hereditary eye diseases, some of which include:

1. Retinitis Pigmentosa - a group of rare, genetic disorders that involve a breakdown and loss of cells in the retina.
2. Macular Degeneration - a progressive disease that damages the central portion of the retina, impairing vision.
3. Glaucoma - a group of eye conditions that damage the optic nerve, often caused by an increase in pressure inside the eye.
4. Cataracts - clouding of the lens inside the eye, which can lead to blurry vision and blindness.
5. Keratoconus - a progressive eye disease that causes the cornea to thin and bulge outward into a cone shape.
6. Color Blindness - a condition where an individual has difficulty distinguishing between certain colors.
7. Optic Neuropathy - damage to the optic nerve, which can result in vision loss.

The symptoms and severity of hereditary eye diseases can vary widely depending on the specific condition and the individual's genetic makeup. Some conditions may be present at birth or develop in early childhood, while others may not appear until later in life. Treatment options for these conditions may include medication, surgery, or lifestyle changes, and are often most effective when started early.

Choroideremia is a rare inherited eye disorder that causes progressive loss of vision. It primarily affects the choroid, which is the layer of blood vessels that provides oxygen and nutrients to the outer layers of the retina. The disease also damages the retina and the optic nerve over time.

The condition is caused by mutations in the CHM gene, which provides instructions for making a protein called REP-1 that is essential for maintaining the health of the light-sensitive cells in the retina (rods and cones). Without this protein, these cells gradually deteriorate and die, leading to vision loss.

Choroideremia typically affects males more severely than females, and it usually begins in childhood with night blindness (nyctalopia) and decreased visual acuity. Over time, the field of vision becomes narrower (tunnel vision), and eventually, complete blindness can occur. Currently, there is no cure for choroideremia, but research is ongoing to develop potential treatments such as gene therapy.

"Miniaturization" is not a term that has a specific medical definition. However, in a broader context, it refers to the process of creating smaller versions of something, usually with the aim of improving functionality, efficiency, or ease of use. In medicine, this concept can be applied to various fields such as medical devices, surgical techniques, and diagnostic tools.

For instance, in interventional radiology, miniaturization refers to the development of smaller and less invasive catheters, wires, and other devices used during minimally invasive procedures. This allows for improved patient outcomes, reduced recovery time, and lower risks of complications compared to traditional open surgical procedures.

Similarly, in pathology, miniaturization can refer to the use of smaller tissue samples or biopsies for diagnostic testing, which can reduce the need for more invasive procedures while still providing accurate results.

Overall, while "miniaturization" is not a medical term per se, it reflects an ongoing trend in medicine towards developing more efficient and less invasive technologies and techniques to improve patient care.

Disease progression is the worsening or advancement of a medical condition over time. It refers to the natural course of a disease, including its development, the severity of symptoms and complications, and the impact on the patient's overall health and quality of life. Understanding disease progression is important for developing appropriate treatment plans, monitoring response to therapy, and predicting outcomes.

The rate of disease progression can vary widely depending on the type of medical condition, individual patient factors, and the effectiveness of treatment. Some diseases may progress rapidly over a short period of time, while others may progress more slowly over many years. In some cases, disease progression may be slowed or even halted with appropriate medical interventions, while in other cases, the progression may be inevitable and irreversible.

In clinical practice, healthcare providers closely monitor disease progression through regular assessments, imaging studies, and laboratory tests. This information is used to guide treatment decisions and adjust care plans as needed to optimize patient outcomes and improve quality of life.

I'm sorry for any confusion, but "lighting" does not have a specific medical definition. In a general context, lighting refers to the arrangement or use of light sources to achieve a particular effect or atmosphere. However, if you are referring to a term in medicine that may be similar to "lighting," you might be thinking of "lumination" or "illumination," which refer to the act of providing or admitting light, especially for medical examination or surgical procedures. I hope this helps! If you have any other questions, please don't hesitate to ask.

Cardiac imaging techniques are diagnostic methods used to visualize and assess the structure and function of the heart. These techniques can be non-invasive or invasive, and they use various forms of energy such as sound waves, radiation, and magnetic fields to produce detailed images of the heart. Some common cardiac imaging techniques include:

1. Echocardiography: This technique uses ultrasound waves to create images of the heart's structure and function. It can provide information about the size and shape of the heart chambers, the thickness and movement of the heart walls, and the valves' function.
2. Cardiac Magnetic Resonance Imaging (MRI): This technique uses a strong magnetic field and radio waves to create detailed images of the heart's structure and function. It can provide information about the size and shape of the heart chambers, the thickness and movement of the heart walls, the valves' function, and the blood flow in the heart.
3. Computed Tomography (CT) Angiography: This technique uses X-rays to create detailed images of the heart's blood vessels. It can provide information about the presence and extent of blockages or narrowing in the coronary arteries.
4. Nuclear Cardiac Imaging: This technique uses small amounts of radioactive substances to produce images of the heart's blood flow. It can provide information about the size and function of the heart chambers, the presence of damaged heart muscle, and the extent of coronary artery disease.
5. Invasive Coronary Angiography: This technique involves inserting a catheter into a blood vessel in the arm or leg and guiding it to the heart's coronary arteries. A contrast dye is then injected through the catheter, and X-ray images are taken to visualize the blood flow in the coronary arteries. This technique can provide detailed information about the presence and extent of blockages or narrowing in the coronary arteries.

A computer system is a collection of hardware and software components that work together to perform specific tasks. This includes the physical components such as the central processing unit (CPU), memory, storage devices, and input/output devices, as well as the operating system and application software that run on the hardware. Computer systems can range from small, embedded systems found in appliances and devices, to large, complex networks of interconnected computers used for enterprise-level operations.

In a medical context, computer systems are often used for tasks such as storing and retrieving electronic health records (EHRs), managing patient scheduling and billing, performing diagnostic imaging and analysis, and delivering telemedicine services. These systems must adhere to strict regulatory standards, such as the Health Insurance Portability and Accountability Act (HIPAA) in the United States, to ensure the privacy and security of sensitive medical information.

The trabecular meshwork is a specialized tissue located in the anterior chamber angle of the eye, near the iris and cornea. It is composed of a network of interconnected beams or trabeculae that provide support and structure to the eye. The primary function of the trabecular meshwork is to regulate the outflow of aqueous humor, the fluid that fills the anterior chamber of the eye, and maintain intraocular pressure within normal ranges.

The aqueous humor flows from the ciliary processes in the posterior chamber of the eye through the pupil and into the anterior chamber. From there, it drains out of the eye through the trabecular meshwork and into the canal of Schlemm, which leads to the venous system. Any obstruction or damage to the trabecular meshwork can lead to an increase in intraocular pressure and potentially contribute to the development of glaucoma, a leading cause of irreversible blindness worldwide.

Computer-assisted surgery (CAS) refers to the use of computer systems and technologies to assist and enhance surgical procedures. These systems can include a variety of tools such as imaging software, robotic systems, and navigation devices that help surgeons plan, guide, and perform surgeries with greater precision and accuracy.

In CAS, preoperative images such as CT scans or MRI images are used to create a three-dimensional model of the surgical site. This model can be used to plan the surgery, identify potential challenges, and determine the optimal approach. During the surgery, the surgeon can use the computer system to navigate and guide instruments with real-time feedback, allowing for more precise movements and reduced risk of complications.

Robotic systems can also be used in CAS to perform minimally invasive procedures with smaller incisions and faster recovery times. The surgeon controls the robotic arms from a console, allowing for greater range of motion and accuracy than traditional hand-held instruments.

Overall, computer-assisted surgery provides a number of benefits over traditional surgical techniques, including improved precision, reduced risk of complications, and faster recovery times for patients.

The posterior segment of the eye refers to the back portion of the interior of the eye, including the vitreous, retina, choroid, and optic nerve. This region is responsible for processing visual information and transmitting it to the brain. The retina contains photoreceptor cells that convert light into electrical signals, which are then sent through the optic nerve to the brain for interpretation as images. Disorders of the posterior eye segment can lead to vision loss or blindness.

Laryngostenosis is a medical term that refers to a condition where the larynx (or voice box) becomes narrowed. This can occur due to various reasons such as scarring, swelling, or growths in the laryngeal area. The narrowing can cause difficulty with breathing, swallowing, and speaking. In severe cases, it may require medical intervention, such as surgery, to correct the problem.

Corneal diseases are a group of disorders that affect the cornea, which is the clear, dome-shaped surface at the front of the eye. The cornea plays an important role in focusing vision, and any damage or disease can cause significant visual impairment or loss. Some common types of corneal diseases include:

1. Keratoconus: A progressive disorder in which the cornea thins and bulges outward into a cone shape, causing distorted vision.
2. Fuchs' dystrophy: A genetic disorder that affects the inner layer of the cornea called the endothelium, leading to swelling, cloudiness, and decreased vision.
3. Dry eye syndrome: A condition in which the eyes do not produce enough tears or the tears evaporate too quickly, causing discomfort, redness, and blurred vision.
4. Corneal ulcers: Open sores on the cornea that can be caused by infection, trauma, or other factors.
5. Herpes simplex keratitis: A viral infection of the cornea that can cause recurrent episodes of inflammation, scarring, and vision loss.
6. Corneal dystrophies: Inherited disorders that affect the structure and clarity of the cornea, leading to visual impairment or blindness.
7. Bullous keratopathy: A condition in which the endothelium fails to pump fluid out of the cornea, causing it to swell and form blisters.
8. Corneal trauma: Injury to the cornea caused by foreign objects, chemicals, or other factors that can lead to scarring, infection, and vision loss.

Treatment for corneal diseases varies depending on the specific condition and severity of the disease. Options may include eyedrops, medications, laser surgery, corneal transplantation, or other treatments.

I'm sorry for any confusion, but "spectrum analysis" is not a commonly used medical term. Spectrum analysis is a term that is more frequently used in the fields of physics, mathematics, and engineering to describe the process of breaking down a signal or a wave into its different frequencies and amplitudes, creating a visual representation called a spectrum.

If you have any concerns about a medical issue, I would recommend consulting with a healthcare professional for accurate information and guidance.

Electroencephalography (EEG) is a medical procedure that records electrical activity in the brain. It uses small, metal discs called electrodes, which are attached to the scalp with paste or a specialized cap. These electrodes detect tiny electrical charges that result from the activity of brain cells, and the EEG machine then amplifies and records these signals.

EEG is used to diagnose various conditions related to the brain, such as seizures, sleep disorders, head injuries, infections, and degenerative diseases like Alzheimer's or Parkinson's. It can also be used during surgery to monitor brain activity and ensure that surgical procedures do not interfere with vital functions.

EEG is a safe and non-invasive procedure that typically takes about 30 minutes to an hour to complete, although longer recordings may be necessary in some cases. Patients are usually asked to relax and remain still during the test, as movement can affect the quality of the recording.

Cortical synchronization refers to the phenomenon of coordinated neural activity in the cerebral cortex, the brain region responsible for higher cognitive functions. It is characterized by the synchronized firing of neurons in various cortical areas, leading to the generation of rhythmic electrical patterns. These rhythms can be observed using electroencephalography (EEG) and other neuroimaging techniques.

Cortical synchronization plays a crucial role in various cognitive processes, such as attention, perception, memory, and consciousness. It is also involved in the pathophysiology of several neurological and psychiatric disorders, including epilepsy, schizophrenia, and Parkinson's disease.

The degree of cortical synchronization can be modulated by various factors, such as sensory stimulation, attention, arousal, and cognitive load. The precise mechanisms underlying cortical synchronization are still not fully understood but are thought to involve complex interactions between excitatory and inhibitory neurons, as well as the modulation of synaptic strength and connectivity.

Laser therapy, also known as phototherapy or laser photobiomodulation, is a medical treatment that uses low-intensity lasers or light-emitting diodes (LEDs) to stimulate healing, reduce pain, and decrease inflammation. It works by promoting the increase of cellular metabolism, blood flow, and tissue regeneration through the process of photobiomodulation.

The therapy can be used on patients suffering from a variety of acute and chronic conditions, including musculoskeletal injuries, arthritis, neuropathic pain, and wound healing complications. The wavelength and intensity of the laser light are precisely controlled to ensure a safe and effective treatment.

During the procedure, the laser or LED device is placed directly on the skin over the area of injury or discomfort. The non-ionizing light penetrates the tissue without causing heat or damage, interacting with chromophores in the cells to initiate a series of photochemical reactions. This results in increased ATP production, modulation of reactive oxygen species, and activation of transcription factors that lead to improved cellular function and reduced pain.

In summary, laser therapy is a non-invasive, drug-free treatment option for various medical conditions, providing patients with an alternative or complementary approach to traditional therapies.

Monoclonal antibodies are laboratory-produced proteins that mimic the immune system's ability to fight off harmful antigens such as viruses and cancer cells. They are created by fusing a single B cell (the type of white blood cell responsible for producing antibodies) with a tumor cell, resulting in a hybrid cell called a hybridoma. This hybridoma can then be cloned to produce a large number of identical cells, all producing the same antibody, hence "monoclonal."

Humanized monoclonal antibodies are a type of monoclonal antibody that have been genetically engineered to include human components. This is done to reduce the risk of an adverse immune response in patients receiving the treatment. In this process, the variable region of the mouse monoclonal antibody, which contains the antigen-binding site, is grafted onto a human constant region. The resulting humanized monoclonal antibody retains the ability to bind to the target antigen while minimizing the immunogenicity associated with murine (mouse) antibodies.

In summary, "antibodies, monoclonal, humanized" refers to a type of laboratory-produced protein that mimics the immune system's ability to fight off harmful antigens, but with reduced immunogenicity due to the inclusion of human components in their structure.

Endotamponade is a medical term that refers to the use of an internal tamponade in ophthalmology, specifically in the treatment of certain eye conditions such as retinal detachment or severe ocular trauma.

In this procedure, a gas or liquid material is injected into the vitreous cavity (the space inside the eye between the lens and the retina) to help reattach the retina to the wall of the eye or to control bleeding inside the eye. The tamponading agent presses against the retina, holding it in place and preventing further fluid from accumulating under it, which can help promote healing and prevent further damage.

The choice of tamponade material depends on the specific condition being treated. For example, a gas bubble may be used for retinal detachment, while silicone oil may be used for more complex cases or where a longer-lasting tamponade is required. The gas or liquid is usually injected through a small incision in the eye and may be left in place for several weeks or months, depending on the individual case.

Overall, endotamponade is an important technique in the management of various retinal disorders and can help preserve vision and prevent blindness in certain cases.

An excimer laser is a type of laser that is used in various medical procedures, particularly in ophthalmology and dermatology. The term "excimer" is derived from "excited dimer," which refers to a short-lived molecule formed when two atoms combine in an excited state.

Excimer lasers emit light at a specific wavelength that is determined by the type of gas used in the laser. In medical applications, excimer lasers typically use noble gases such as argon, krypton, or xenon, combined with halogens such as fluorine or chlorine. The most commonly used excimer laser in medical procedures is the excimer laser that uses a mixture of argon and fluoride gas to produce light at a wavelength of 193 nanometers (nm).

In ophthalmology, excimer lasers are primarily used for refractive surgery, such as LASIK and PRK, to correct vision problems like myopia, hyperopia, and astigmatism. The laser works by vaporizing tiny amounts of tissue from the cornea, reshaping its curvature to improve the way light is focused onto the retina.

In dermatology, excimer lasers are used for various skin conditions, including psoriasis, vitiligo, and atopic dermatitis. The laser works by emitting high-energy ultraviolet (UV) light that selectively targets and destroys the abnormal cells responsible for these conditions while leaving surrounding healthy tissue intact.

Excimer lasers are known for their precision, accuracy, and minimal side effects, making them a popular choice in medical procedures where fine detail and tissue preservation are critical.

Prosthesis implantation is a surgical procedure where an artificial device or component, known as a prosthesis, is placed inside the body to replace a missing or damaged body part. The prosthesis can be made from various materials such as metal, plastic, or ceramic and is designed to perform the same function as the original body part.

The implantation procedure involves making an incision in the skin to create a pocket where the prosthesis will be placed. The prosthesis is then carefully positioned and secured in place using screws, cement, or other fixation methods. In some cases, tissue from the patient's own body may be used to help anchor the prosthesis.

Once the prosthesis is in place, the incision is closed with sutures or staples, and the area is bandaged. The patient will typically need to undergo rehabilitation and physical therapy to learn how to use the new prosthesis and regain mobility and strength.

Prosthesis implantation is commonly performed for a variety of reasons, including joint replacement due to arthritis or injury, dental implants to replace missing teeth, and breast reconstruction after mastectomy. The specific procedure and recovery time will depend on the type and location of the prosthesis being implanted.

The corneal stroma, also known as the substantia propria, is the thickest layer of the cornea, which is the clear, dome-shaped surface at the front of the eye. The cornea plays a crucial role in focusing vision.

The corneal stroma makes up about 90% of the cornea's thickness and is composed of parallel bundles of collagen fibers that are arranged in regular, repeating patterns. These fibers give the cornea its strength and transparency. The corneal stroma also contains a small number of cells called keratocytes, which produce and maintain the collagen fibers.

Disorders that affect the corneal stroma can cause vision loss or other eye problems. For example, conditions such as keratoconus, in which the cornea becomes thin and bulges outward, can distort vision and make it difficult to see clearly. Other conditions, such as corneal scarring or infection, can also affect the corneal stroma and lead to vision loss or other eye problems.

Eye diseases are a range of conditions that affect the eye or visual system, causing damage to vision and, in some cases, leading to blindness. These diseases can be categorized into various types, including:

1. Refractive errors: These include myopia (nearsightedness), hyperopia (farsightedness), astigmatism, and presbyopia, which affect the way light is focused on the retina and can usually be corrected with glasses or contact lenses.
2. Cataracts: A clouding of the lens inside the eye that leads to blurry vision, glare, and decreased contrast sensitivity. Cataract surgery is the most common treatment for this condition.
3. Glaucoma: A group of diseases characterized by increased pressure in the eye, leading to damage to the optic nerve and potential blindness if left untreated. Treatment includes medications, laser therapy, or surgery.
4. Age-related macular degeneration (AMD): A progressive condition that affects the central part of the retina called the macula, causing blurry vision and, in advanced stages, loss of central vision. Treatment may include anti-VEGF injections, laser therapy, or nutritional supplements.
5. Diabetic retinopathy: A complication of diabetes that affects the blood vessels in the retina, leading to bleeding, leakage, and potential blindness if left untreated. Treatment includes laser therapy, anti-VEGF injections, or surgery.
6. Retinal detachment: A separation of the retina from its underlying tissue, which can lead to vision loss if not treated promptly with surgery.
7. Amblyopia (lazy eye): A condition where one eye does not develop normal vision, often due to a misalignment or refractive error in childhood. Treatment includes correcting the underlying problem and encouraging the use of the weaker eye through patching or other methods.
8. Strabismus (crossed eyes): A misalignment of the eyes that can lead to amblyopia if not treated promptly with surgery, glasses, or other methods.
9. Corneal diseases: Conditions that affect the transparent outer layer of the eye, such as keratoconus, Fuchs' dystrophy, and infectious keratitis, which can lead to vision loss if not treated promptly.
10. Uveitis: Inflammation of the middle layer of the eye, which can cause vision loss if not treated promptly with anti-inflammatory medications or surgery.

A pupil disorder refers to any abnormality or condition affecting the size, shape, or reactivity of the pupils, the circular black openings in the center of the eyes through which light enters. The pupil's primary function is to regulate the amount of light that reaches the retina, adjusting its size accordingly.

There are several types of pupil disorders, including:

1. Anisocoria: A condition characterized by unequal pupil sizes in either one or both eyes. This may be caused by various factors, such as nerve damage, trauma, inflammation, or medication side effects.

2. Horner's syndrome: A neurological disorder affecting the autonomic nervous system, resulting in a smaller pupil (miosis), partial eyelid droop (ptosis), and decreased sweating (anhidrosis) on the same side of the face. It is caused by damage to the sympathetic nerve pathway.

3. Adie's tonic pupil: A condition characterized by a dilated, poorly reactive pupil due to damage to the ciliary ganglion or short ciliary nerves. This disorder usually affects one eye and may be associated with decreased deep tendon reflexes in the affected limbs.

4. Argyll Robertson pupil: A condition where the pupils are small, irregularly shaped, and do not react to light but constrict when focusing on nearby objects (accommodation). This disorder is often associated with neurosyphilis or other brainstem disorders.

5. Pupillary dilation: Abnormally dilated pupils can be a sign of various conditions, such as drug use (e.g., atropine, cocaine), brainstem injury, Adie's tonic pupil, or oculomotor nerve palsy.

6. Pupillary constriction: Abnormally constricted pupils can be a sign of various conditions, such as Horner's syndrome, Argyll Robertson pupil, drug use (e.g., opioids, pilocarpine), or oculomotor nerve palsy.

7. Light-near dissociation: A condition where the pupils do not react to light but constrict when focusing on nearby objects. This can be seen in Argyll Robertson pupil and Adie's tonic pupil.

Prompt evaluation by an ophthalmologist or neurologist is necessary for accurate diagnosis and management of these conditions.

The brain is the central organ of the nervous system, responsible for receiving and processing sensory information, regulating vital functions, and controlling behavior, movement, and cognition. It is divided into several distinct regions, each with specific functions:

1. Cerebrum: The largest part of the brain, responsible for higher cognitive functions such as thinking, learning, memory, language, and perception. It is divided into two hemispheres, each controlling the opposite side of the body.
2. Cerebellum: Located at the back of the brain, it is responsible for coordinating muscle movements, maintaining balance, and fine-tuning motor skills.
3. Brainstem: Connects the cerebrum and cerebellum to the spinal cord, controlling vital functions such as breathing, heart rate, and blood pressure. It also serves as a relay center for sensory information and motor commands between the brain and the rest of the body.
4. Diencephalon: A region that includes the thalamus (a major sensory relay station) and hypothalamus (regulates hormones, temperature, hunger, thirst, and sleep).
5. Limbic system: A group of structures involved in emotional processing, memory formation, and motivation, including the hippocampus, amygdala, and cingulate gyrus.

The brain is composed of billions of interconnected neurons that communicate through electrical and chemical signals. It is protected by the skull and surrounded by three layers of membranes called meninges, as well as cerebrospinal fluid that provides cushioning and nutrients.

The larynx, also known as the voice box, is a complex structure in the neck that plays a crucial role in protection of the lower respiratory tract and in phonation. It is composed of cartilaginous, muscular, and soft tissue structures. The primary functions of the larynx include:

1. Airway protection: During swallowing, the larynx moves upward and forward to close the opening of the trachea (the glottis) and prevent food or liquids from entering the lungs. This action is known as the swallowing reflex.
2. Phonation: The vocal cords within the larynx vibrate when air passes through them, producing sound that forms the basis of human speech and voice production.
3. Respiration: The larynx serves as a conduit for airflow between the upper and lower respiratory tracts during breathing.

The larynx is located at the level of the C3-C6 vertebrae in the neck, just above the trachea. It consists of several important structures:

1. Cartilages: The laryngeal cartilages include the thyroid, cricoid, and arytenoid cartilages, as well as the corniculate and cuneiform cartilages. These form a framework for the larynx and provide attachment points for various muscles.
2. Vocal cords: The vocal cords are thin bands of mucous membrane that stretch across the glottis (the opening between the arytenoid cartilages). They vibrate when air passes through them, producing sound.
3. Muscles: There are several intrinsic and extrinsic muscles associated with the larynx. The intrinsic muscles control the tension and position of the vocal cords, while the extrinsic muscles adjust the position and movement of the larynx within the neck.
4. Nerves: The larynx is innervated by both sensory and motor nerves. The recurrent laryngeal nerve provides motor innervation to all intrinsic laryngeal muscles, except for one muscle called the cricothyroid, which is innervated by the external branch of the superior laryngeal nerve. Sensory innervation is provided by the internal branch of the superior laryngeal nerve and the recurrent laryngeal nerve.

The larynx plays a crucial role in several essential functions, including breathing, speaking, and protecting the airway during swallowing. Dysfunction or damage to the larynx can result in various symptoms, such as hoarseness, difficulty swallowing, shortness of breath, or stridor (a high-pitched sound heard during inspiration).

Tunica intima, also known as the intima layer, is the innermost layer of a blood vessel, including arteries and veins. It is in direct contact with the flowing blood and is composed of simple squamous endothelial cells that form a continuous, non-keratinized, stratified epithelium. These cells play a crucial role in maintaining vascular homeostasis by regulating the passage of molecules and immune cells between the blood and the vessel wall, as well as contributing to the maintenance of blood fluidity and preventing coagulation.

The tunica intima is supported by a thin layer of connective tissue called the basement membrane, which provides structural stability and anchorage for the endothelial cells. Beneath the basement membrane lies a loose network of elastic fibers and collagen, known as the internal elastic lamina, that separates the tunica intima from the middle layer, or tunica media.

In summary, the tunica intima is the innermost layer of blood vessels, primarily composed of endothelial cells and a basement membrane, which regulates various functions to maintain vascular homeostasis.

Acoustics is a branch of physics that deals with the study of sound, its production, transmission, and effects. In a medical context, acoustics may refer to the use of sound waves in medical procedures such as:

1. Diagnostic ultrasound: This technique uses high-frequency sound waves to create images of internal organs and tissues. It is commonly used during pregnancy to monitor fetal development, but it can also be used to diagnose a variety of medical conditions, including heart disease, cancer, and musculoskeletal injuries.
2. Therapeutic ultrasound: This technique uses low-frequency sound waves to promote healing and reduce pain and inflammation in muscles, tendons, and ligaments. It is often used to treat soft tissue injuries, arthritis, and other musculoskeletal conditions.
3. Otology: Acoustics also plays a crucial role in the field of otology, which deals with the study and treatment of hearing and balance disorders. The shape, size, and movement of the outer ear, middle ear, and inner ear all affect how sound waves are transmitted and perceived. Abnormalities in any of these structures can lead to hearing loss, tinnitus, or balance problems.

In summary, acoustics is an important field of study in medicine that has applications in diagnosis, therapy, and the understanding of various medical conditions related to sound and hearing.

Color vision defects, also known as color blindness, are conditions in which a person has difficulty distinguishing between certain colors. The most common types of color vision defects involve the inability to distinguish between red and green or blue and yellow. These deficiencies result from an alteration or absence of one or more of the three types of cone cells in the retina that are responsible for normal color vision.

In red-green color vision defects, there is a problem with either the red or green cones, or both. This results in difficulty distinguishing between these two colors and their shades. Protanopia is a type of red-green color vision defect where there is an absence of red cone cells, making it difficult to distinguish between red and green as well as between red and black or green and black. Deuteranopia is another type of red-green color vision defect where there is an absence of green cone cells, resulting in similar difficulties distinguishing between red and green, as well as between blue and yellow.

Blue-yellow color vision defects are less common than red-green color vision defects. Tritanopia is a type of blue-yellow color vision defect where there is an absence of blue cone cells, making it difficult to distinguish between blue and yellow, as well as between blue and purple or yellow and pink.

Color vision defects are usually inherited and present from birth, but they can also result from eye diseases, chemical exposure, aging, or medication side effects. They affect both men and women, although red-green color vision defects are more common in men than in women. People with color vision defects may have difficulty with tasks that require color discrimination, such as matching clothes, selecting ripe fruit, reading colored maps, or identifying warning signals. However, most people with mild to moderate color vision defects can adapt and function well in daily life.

An Eye Bank is an organization that collects, stores, and distributes donated human eyes for corneal transplantation and other ocular medical research purposes. The eye bank's primary function is to ensure the quality of the donated tissue and make it available for those in need of sight-restoring procedures.

The cornea, the clear front part of the eye, can be surgically transplanted from a deceased donor to a recipient with corneal damage or disease, thereby improving or restoring their vision. The eye bank's role includes obtaining consent for donation, retrieving the eyes from the donor, evaluating the tissue for suitability, preserving it properly, and then allocating it to surgeons for transplantation.

Eye banks follow strict medical guidelines and adhere to ethical standards to ensure the safety and quality of the donated tissues. The process involves screening potential donors for infectious diseases and other conditions that may affect the quality or safety of the cornea. Once deemed suitable, the corneas are carefully removed, preserved in specific solutions, and stored until they are needed for transplantation.

In addition to corneal transplants, eye banks also support research and education in ophthalmology by providing human eye tissues for various studies aimed at advancing our understanding of eye diseases and developing new treatments.

The "subtraction technique" is not a widely recognized or established term in medical terminology. It may refer to various methods used in different medical contexts that involve subtracting or comparing measurements, values, or observations to diagnose, monitor, or treat medical conditions. However, without more specific context, it's difficult to provide an accurate medical definition of the term.

In radiology, for example, the subtraction technique is a method used in imaging to enhance the visibility of certain structures by digitally subtracting one image from another. This technique is often used in angiography to visualize blood vessels more clearly.

Therefore, it's essential to provide more context or specify the medical field when using the term "subtraction technique" to ensure accurate communication and understanding.

Calcinosis is a medical condition characterized by the abnormal deposit of calcium salts in various tissues of the body, commonly under the skin or in the muscles and tendons. These calcium deposits can form hard lumps or nodules that can cause pain, inflammation, and restricted mobility. Calcinosis can occur as a complication of other medical conditions, such as autoimmune disorders, kidney disease, and hypercalcemia (high levels of calcium in the blood). In some cases, the cause of calcinosis may be unknown. Treatment for calcinosis depends on the underlying cause and may include medications to manage calcium levels, physical therapy, and surgical removal of large deposits.

A rupture, in medical terms, refers to the breaking or tearing of an organ, tissue, or structure in the body. This can occur due to various reasons such as trauma, injury, increased pressure, or degeneration. A ruptured organ or structure can lead to serious complications, including internal bleeding, infection, and even death, if not treated promptly and appropriately. Examples of ruptures include a ruptured appendix, ruptured eardrum, or a ruptured disc in the spine.

Parasitic eye infections are conditions characterized by the invasion and infestation of the eye or its surrounding structures by parasites. These can be protozoans, helminths, or ectoparasites. Examples of such infections include Acanthamoeba keratitis, which is caused by a free-living amoeba found in water and soil; Toxoplasmosis, which is caused by the protozoan Toxoplasma gondii; Loiasis, which is caused by the parasitic filarial worm Loa loa; and Demodicosis, which is caused by the mite Demodex folliculorum. Symptoms can vary depending on the type of parasite but often include redness, pain, discharge, and vision changes. Treatment typically involves antiparasitic medications and sometimes surgery to remove the parasites or damaged tissue. Prevention measures include good hygiene practices and avoiding contact with contaminated water or soil.

A retinal hemorrhage is a type of bleeding that occurs in the blood vessels of the retina, which is the light-sensitive tissue located at the back of the eye. This condition can result from various underlying causes, including diabetes, high blood pressure, age-related macular degeneration, or trauma to the eye. Retinal hemorrhages can be categorized into different types based on their location and appearance, such as dot and blot hemorrhages, flame-shaped hemorrhages, or subhyaloid hemorrhages. Depending on the severity and cause of the hemorrhage, treatment options may vary from monitoring to laser therapy, medication, or even surgery. It is essential to consult an ophthalmologist for a proper evaluation and management plan if you suspect a retinal hemorrhage.

Intraocular lens (IOL) implantation is a surgical procedure that involves placing a small artificial lens inside the eye to replace the natural lens that has been removed. This procedure is typically performed during cataract surgery, where the cloudy natural lens is removed and replaced with an IOL to restore clear vision.

During the procedure, a small incision is made in the eye, and the cloudy lens is broken up and removed using ultrasound waves or laser energy. Then, the folded IOL is inserted through the same incision and positioned in the correct place inside the eye. Once in place, the IOL unfolds and is secured into position.

There are several types of IOLs available, including monofocal, multifocal, toric, and accommodating lenses. Monofocal lenses provide clear vision at one distance, while multifocal lenses offer clear vision at multiple distances. Toric lenses correct astigmatism, and accommodating lenses can change shape to focus on objects at different distances.

Overall, intraocular lens implantation is a safe and effective procedure that can help restore clear vision in patients with cataracts or other eye conditions that require the removal of the natural lens.

Pseudophakia is a medical term that refers to the condition where a person's natural lens in the eye has been replaced with an artificial one. This procedure is typically performed during cataract surgery, where the cloudy, natural lens is removed and replaced with a clear, artificial lens to improve vision. The prefix "pseudo" means false or fake, and "phakia" refers to the natural lens of the eye, hence the term "Pseudophakia" implies a false or artificial lens.

An optical device is not a medical term per se, but rather a general term that describes any instrument or tool that uses light or electromagnetic radiation in the visible spectrum to observe, measure, or manipulate objects or phenomena. However, there are several optical devices that are commonly used in medical settings and have specific medical definitions. Here are some examples:

1. Ophthalmoscope: A handheld device used by healthcare professionals to examine the interior of the eye, including the retina, optic nerve, and vitreous humor. It typically consists of a handle, a light source, and a set of lenses that can be adjusted to focus on different parts of the eye.
2. Slit lamp: A specialized microscope used in ophthalmology to examine the structures of the eye at high magnification. It uses a narrow beam of light to illuminate the eye and allows the examiner to visualize details such as corneal abrasions, cataracts, and retinal lesions.
3. Microscope: A device that uses a system of lenses or mirrors to magnify objects or images, making them visible to the human eye. Microscopes are used in various medical fields, including pathology, hematology, and microbiology, to examine specimens such as tissues, cells, and microorganisms.
4. Endoscope: A flexible tube equipped with a light source and a camera that can be inserted into body cavities or passages to visualize internal structures. Endoscopes are used in procedures such as colonoscopy, gastroscopy, and laparoscopy to diagnose and treat conditions such as polyps, ulcers, and tumors.
5. Otoscope: A device used by healthcare professionals to examine the ear canal and eardrum. It typically consists of a handle, a light source, and a speculum that can be inserted into the ear canal to visualize the eardrum and identify any abnormalities such as inflammation, infection, or foreign bodies.
6. Refractor: A device used in optometry to measure the refractive error of the eye, or the amount of lens power needed to correct vision. The patient looks through a series of lenses while reading an eye chart, and the optometrist adjusts the lenses until the clearest vision is achieved.
7. Slit lamp: A microscope used in ophthalmology to examine the structures of the eye, including the cornea, iris, lens, and retina. The slit lamp uses a narrow beam of light to illuminate the eye and allow for detailed examination of any abnormalities or diseases.

Retinal artery occlusion (RAO) is a medical condition characterized by the blockage or obstruction of the retinal artery, which supplies oxygenated blood to the retina. This blockage typically occurs due to embolism (a small clot or debris that travels to the retinal artery), thrombosis (blood clot formation in the artery), or vasculitis (inflammation of the blood vessels).

There are two types of retinal artery occlusions:

1. Central Retinal Artery Occlusion (CRAO): This type occurs when the main retinal artery is obstructed, affecting the entire inner layer of the retina. It can lead to severe and sudden vision loss in the affected eye.
2. Branch Retinal Artery Occlusion (BRAO): This type affects a branch of the retinal artery, causing visual field loss in the corresponding area. Although it is less severe than CRAO, it can still result in noticeable vision impairment.

Immediate medical attention is crucial for both types of RAO to improve the chances of recovery and minimize potential damage to the eye and vision. Treatment options may include medications, laser therapy, or surgery, depending on the underlying cause and the severity of the condition.

Eye abnormalities refer to any structural or functional anomalies that affect the eye or its surrounding tissues. These abnormalities can be present at birth (congenital) or acquired later in life due to various factors such as injury, disease, or aging. Some examples of eye abnormalities include:

1. Strabismus: Also known as crossed eyes, strabismus is a condition where the eyes are misaligned and point in different directions.
2. Nystagmus: This is an involuntary movement of the eyes that can be horizontal, vertical, or rotatory.
3. Cataracts: A cataract is a clouding of the lens inside the eye that can cause vision loss.
4. Glaucoma: This is a group of eye conditions that damage the optic nerve and can lead to vision loss.
5. Retinal disorders: These include conditions such as retinal detachment, macular degeneration, and diabetic retinopathy.
6. Corneal abnormalities: These include conditions such as keratoconus, corneal ulcers, and Fuchs' dystrophy.
7. Orbital abnormalities: These include conditions such as orbital tumors, thyroid eye disease, and Graves' ophthalmopathy.
8. Ptosis: This is a condition where the upper eyelid droops over the eye.
9. Color blindness: A condition where a person has difficulty distinguishing between certain colors.
10. Microphthalmia: A condition where one or both eyes are abnormally small.

These are just a few examples of eye abnormalities, and there are many others that can affect the eye and its functioning. If you suspect that you have an eye abnormality, it is important to consult with an ophthalmologist for proper diagnosis and treatment.

Ocular accommodation is the process by which the eye changes optical power to maintain a clear image or focus on an object as its distance varies. This is primarily achieved by the lens of the eye changing shape through the action of the ciliary muscles inside the eye. When you look at something far away, the lens becomes flatter, and when you look at something close up, the lens thickens. This ability to adjust focus allows for clear vision at different distances.

Scleral buckling is a surgical procedure used to treat retinal detachment, a serious eye condition that can cause vision loss. In this procedure, the sclera (the white outer coat of the eye) is "buckled" or indented with a piece of silicone rubber or sponge material. This brings the detached retina into contact with the wall of the eye, allowing the retina to reattach and heal. The buckle is usually left in place permanently. Scleral buckling has been a standard treatment for retinal detachment for many years and is often combined with vitrectomy or cryotherapy to improve outcomes.

Animal disease models are specialized animals, typically rodents such as mice or rats, that have been genetically engineered or exposed to certain conditions to develop symptoms and physiological changes similar to those seen in human diseases. These models are used in medical research to study the pathophysiology of diseases, identify potential therapeutic targets, test drug efficacy and safety, and understand disease mechanisms.

The genetic modifications can include knockout or knock-in mutations, transgenic expression of specific genes, or RNA interference techniques. The animals may also be exposed to environmental factors such as chemicals, radiation, or infectious agents to induce the disease state.

Examples of animal disease models include:

1. Mouse models of cancer: Genetically engineered mice that develop various types of tumors, allowing researchers to study cancer initiation, progression, and metastasis.
2. Alzheimer's disease models: Transgenic mice expressing mutant human genes associated with Alzheimer's disease, which exhibit amyloid plaque formation and cognitive decline.
3. Diabetes models: Obese and diabetic mouse strains like the NOD (non-obese diabetic) or db/db mice, used to study the development of type 1 and type 2 diabetes, respectively.
4. Cardiovascular disease models: Atherosclerosis-prone mice, such as ApoE-deficient or LDLR-deficient mice, that develop plaque buildup in their arteries when fed a high-fat diet.
5. Inflammatory bowel disease models: Mice with genetic mutations affecting intestinal barrier function and immune response, such as IL-10 knockout or SAMP1/YitFc mice, which develop colitis.

Animal disease models are essential tools in preclinical research, but it is important to recognize their limitations. Differences between species can affect the translatability of results from animal studies to human patients. Therefore, researchers must carefully consider the choice of model and interpret findings cautiously when applying them to human diseases.

In medical terms, fingers are not specifically defined as they are common anatomical structures. However, I can provide you with a general anatomy definition:

Fingers are the terminal parts of the upper limb in primates, including humans, consisting of four digits (thumb, index, middle, and ring fingers) and one opposable thumb. They contain bones called phalanges, connected by joints that allow for movement and flexibility. Each finger has a nail, nerve endings for sensation, and blood vessels to supply nutrients and oxygen. Fingers are crucial for various activities such as grasping, manipulating objects, and tactile exploration of the environment.

Angioid streaks are abnormal, jagged lines or cracks in the delicate tissue at the back of the eye called the retina. These streaks typically occur near the optic nerve and radiate outward toward the edges of the retina. They are caused by degeneration of the underlying tissue, called Bruch's membrane, which separates the retina from the choroid, a layer of blood vessels that provides nutrients to the retina.

Angioid streaks are often associated with various medical conditions, including pseudoxanthoma elasticum, Paget's disease of bone, Ehlers-Danlos syndrome, and sickle cell anemia. They can also be a complication of cataract surgery or other eye trauma.

While angioid streaks themselves do not cause vision loss, they can lead to serious complications such as retinal hemorrhage, scarring, and detachment, which can result in significant vision loss if left untreated. Regular eye examinations are recommended for individuals with angioid streaks to monitor for any changes or complications that may require treatment.

Eye proteins, also known as ocular proteins, are specific proteins that are found within the eye and play crucial roles in maintaining proper eye function and health. These proteins can be found in various parts of the eye, including the cornea, iris, lens, retina, and other structures. They perform a wide range of functions, such as:

1. Structural support: Proteins like collagen and elastin provide strength and flexibility to the eye's tissues, enabling them to maintain their shape and withstand mechanical stress.
2. Light absorption and transmission: Proteins like opsins and crystallins are involved in capturing and transmitting light signals within the eye, which is essential for vision.
3. Protection against damage: Some eye proteins, such as antioxidant enzymes and heat shock proteins, help protect the eye from oxidative stress, UV radiation, and other environmental factors that can cause damage.
4. Regulation of eye growth and development: Various growth factors and signaling molecules, which are protein-based, contribute to the proper growth, differentiation, and maintenance of eye tissues during embryonic development and throughout adulthood.
5. Immune defense: Proteins involved in the immune response, such as complement components and immunoglobulins, help protect the eye from infection and inflammation.
6. Maintenance of transparency: Crystallin proteins in the lens maintain its transparency, allowing light to pass through unobstructed for clear vision.
7. Neuroprotection: Certain eye proteins, like brain-derived neurotrophic factor (BDNF), support the survival and function of neurons within the retina, helping to preserve vision.

Dysfunction or damage to these eye proteins can contribute to various eye disorders and diseases, such as cataracts, age-related macular degeneration, glaucoma, diabetic retinopathy, and others.

The tympanic membrane, also known as the eardrum, is a thin, cone-shaped membrane that separates the external auditory canal from the middle ear. It serves to transmit sound vibrations from the air to the inner ear, where they are converted into electrical signals that can be interpreted by the brain as sound. The tympanic membrane is composed of three layers: an outer layer of skin, a middle layer of connective tissue, and an inner layer of mucous membrane. It is held in place by several small bones and muscles and is highly sensitive to changes in pressure.

Dry eye syndrome, also known as keratoconjunctivitis sicca, is a condition characterized by insufficient lubrication and moisture of the eyes. This occurs when the tears produced by the eyes are not sufficient in quantity or quality to keep the eyes moist and comfortable. The medical definition of dry eye syndromes includes the following symptoms:

1. A gritty or sandy sensation in the eyes
2. Burning or stinging sensations
3. Redness and irritation
4. Blurred vision that improves with blinking
5. Light sensitivity
6. A feeling of something foreign in the eye
7. Stringy mucus in or around the eyes
8. Difficulty wearing contact lenses
9. Watery eyes, which may seem contradictory but can be a response to dryness
10. Eye fatigue and discomfort after prolonged screen time or reading

The causes of dry eye syndromes can include aging, hormonal changes, certain medical conditions (such as diabetes, rheumatoid arthritis, lupus, Sjogren's syndrome), medications (antihistamines, decongestants, antidepressants, birth control pills), environmental factors (dry air, wind, smoke, dust), and prolonged screen time or reading.

Treatment for dry eye syndromes depends on the severity of the condition and its underlying causes. It may include artificial tears, lifestyle changes, prescription medications, and in some cases, surgical procedures to improve tear production or drainage.

Emmetropia is a term used in optometry and ophthalmology to describe a state where the eye's optical power is perfectly matched to the length of the eye. As a result, light rays entering the eye are focused directly on the retina, creating a clear image without the need for correction with glasses or contact lenses. It is the opposite of myopia (nearsightedness), hyperopia (farsightedness), or astigmatism, where the light rays are not properly focused on the retina, leading to blurry vision. Emmetropia is considered a normal and ideal eye condition.

Multiple Sclerosis (MS) is a chronic autoimmune disease that affects the central nervous system (CNS), which includes the brain, spinal cord, and optic nerves. In MS, the immune system mistakenly attacks the protective covering of nerve fibers, called myelin, leading to damage and scarring (sclerosis). This results in disrupted communication between the brain and the rest of the body, causing a variety of neurological symptoms that can vary widely from person to person.

The term "multiple" refers to the numerous areas of scarring that occur throughout the CNS in this condition. The progression, severity, and specific symptoms of MS are unpredictable and may include vision problems, muscle weakness, numbness or tingling, difficulty with balance and coordination, cognitive impairment, and mood changes. There is currently no cure for MS, but various treatments can help manage symptoms, modify the course of the disease, and improve quality of life for those affected.

Elasticity imaging techniques are non-invasive medical diagnostic methods used to evaluate the stiffness or elasticity of various tissues in the body, such as organs, muscles, and breast tissue. These techniques can help detect and diagnose abnormalities, including tumors, lesions, and other conditions that may affect tissue stiffness.

There are several types of elasticity imaging techniques, including:

1. Ultrasound Elastography: This technique uses ultrasound waves to apply pressure to tissues and measure their deformation or strain. The degree of deformation is then used to calculate the stiffness of the tissue.
2. Magnetic Resonance Elastography (MRE): MRE uses magnetic resonance imaging (MRI) to create images of tissue elasticity. A mechanical device is used to apply vibrations to the body, and the resulting motion is measured using MRI to determine tissue stiffness.
3. Shear Wave Elastography: This technique uses acoustic radiation force impulses to generate shear waves in tissues. The speed of these waves is then measured to calculate tissue stiffness.
4. Strain Imaging: This technique measures the amount of deformation or strain that occurs in tissues when they are compressed or stretched. It can be used to detect areas of increased stiffness, such as tumors or scar tissue.

Elasticity imaging techniques have several advantages over traditional diagnostic methods, including their non-invasive nature and ability to provide real-time images of tissue elasticity. They are also useful for monitoring changes in tissue stiffness over time, making them valuable tools for evaluating the effectiveness of treatments and monitoring disease progression.

Angiography is a medical procedure in which an x-ray image is taken to visualize the internal structure of blood vessels, arteries, or veins. This is done by injecting a radiopaque contrast agent (dye) into the blood vessel using a thin, flexible catheter. The dye makes the blood vessels visible on an x-ray image, allowing doctors to diagnose and treat various medical conditions such as blockages, narrowing, or malformations of the blood vessels.

There are several types of angiography, including:

* Cardiac angiography (also called coronary angiography) - used to examine the blood vessels of the heart
* Cerebral angiography - used to examine the blood vessels of the brain
* Peripheral angiography - used to examine the blood vessels in the limbs or other parts of the body.

Angiography is typically performed by a radiologist, cardiologist, or vascular surgeon in a hospital setting. It can help diagnose conditions such as coronary artery disease, aneurysms, and peripheral arterial disease, among others.

... (OCT) is an imaging technique that uses interferometry with short-coherence-length light to obtain ... Optical coherence tomography (OCT) is a technique for obtaining sub-surface images of translucent or opaque materials at a ... "optical coherence tomography". Since then, OCT with micrometer resolution and cross-sectional imaging capabilities has become a ... The optical setup typically consists of an interferometer (Fig. 1, typically Michelson type) with a low coherence, broad ...
"Temporal coherence and time-frequency distributions in spectroscopic optical coherence tomography". Journal of the Optical ... Spectroscopic optical coherence tomography (SOCT) is an optical imaging and sensing technique, which provides localized ... Optical coherence tomography : technology and applications. Drexler, Wolfgang,, Fujimoto, James G. (Second ed.). Cham. ISBN 978 ... spectroscopic information of a sample based on the principles of optical coherence tomography (OCT) and low coherence ...
... (Q-OCT) is an imaging technique that uses nonclassical (quantum) light sources to generate ... "Quantum optical coherence tomography data collection apparatus and method for processing therefor". 2002-11-26. Nasr, Magued B ... Lavoie, J.; Kaltenbaek, R.; Resch, K. J. (2009-03-02). "Quantum-optical coherence tomography with classical light". Optics ... "Quantum-optical coherence tomography with dispersion cancellation". Physical Review A. 65 (5): 053817. arXiv:quant-ph/0111140. ...
... (OCTA) is a non-invasive imaging technique based on optical coherence tomography (OCT ... OCTA may make use of speckle variance optical coherence tomography. OCTA uses low-coherence interferometry to measure changes ... Freiberg FJ, Pfau M, Wons J, Wirth MA, Becker MD, Michels S (June 2016). "Optical coherence tomography angiography of the ... Wons J, Pfau M, Wirth MA, Freiberg FJ, Becker MD, Michels S (2016). "Optical Coherence Tomography Angiography of the Foveal ...
... (OCT) (or, more generally, intravascular optical coherence tomography, IVOCT) is an ... State-of-the-art intracoronary optical coherence tomography uses a swept-source laser to make OCT images at high-speed (i.e., ... Intracoronary optical coherence tomography was demonstrated to be safe among heterogeneous groups of patients presenting ... Swanson, Eric (13 June 2016). "Optical Coherence Tomography: Beyond better clinical care: OCT's economic impact". BioOptics ...
... is an extension of OCT, where it combines the Doppler effect principle to achieve high ... Optical coherence tomography (OCT) is a technique that displays images of the tissue by using the backscattered light.[citation ... Not only conserving the excellence of OCT, Doppler Optical Coherence Tomography also combines the Doppler effect principle as a ... 25, 1358 (2000) Yang, Victor X. D. (Victor Xiao Dong) (2004). Endoscopic Doppler Optical Coherence Tomography [microform]. ...
... (SV-OCT) is an imaging algorithm for functional optical imaging. Optical ... OCT can be used to capture functional images of blood flow, a technique known as optical coherence tomography angiography (OCT- ... Choma, Michael A.; Hsu, Kevin; Izatt, Joseph A. (2005). "Swept source optical coherence tomography using an all-fiber 1300-nm ... Grishina, Olga A.; Wang, Shang; Larina, Irina V. (2017). "Speckle variance optical coherence tomography of blood flow in the ...
... (DA-OCT) is an imaging modality that is based on the principles of optical coherence ... Angle-resolved low-coherence interferometry Ballistic photon Interferometry Medical imaging Optical coherence tomography ... "Optical Coherence Tomography: An Emerging Technology for Biomedical Imaging and Optical Biopsy". Neoplasia. 2 (1): 9-25. doi: ... Gora, Michalina J.; Suter, Melissa J.; Tearney, Guillermo J.; Li, Xingde (2017-05-01). "Endoscopic optical coherence tomography ...
Optical coherence tomography. Spie Milestone Series MS. 1998;147:324-7. Romero-Borja F, Venkateswaran K, Roorda A, Hebert T. " ... Optical coherence tomography (OCT) represents a powerful clinical tool for monitoring retinal physiology in patients. OCT uses ... "Comparison between optical coherence tomography and fundus fluorescein angiography for the detection of cystoid macular edema ... with adaptive optics enhanced scanning laser ophthalmoscopy and high-speed transversal scanning optical coherence tomography". ...
He is known for his leading role in the invention of a novel medical imaging modality named optical coherence tomography that ... Boyd, Kierstan (14 October 2015). "What Is Optical Coherence Tomography?". American Academy of Ophthalmology. Retrieved 8 ... Optical coherence tomography, Fellows of the American Physical Society, Fellows of the American Association for the Advancement ... "Optical Coherence Tomography". Science. 254 (5035): 1178-1181. Bibcode:1991Sci...254.1178H. doi:10.1126/science.1957169. PMC ...
"Theory of Optical Coherence Tomography". In Drexler; Fujimoto (eds.). Optical Coherence Tomography. Springer Berlin Heidelberg ... In optical communications and optical coherence tomography (OCT), assuming that the source has a Gaussian emission spectrum, ... Physics portal Coherence time Superconducting coherence length Spatial coherence Akcay, C.; Parrein, P.; Rolland, J.P. (2002 ... The coherence length can also be measured using a Michelson interferometer and is the optical path length difference of a self- ...
"Articles that mention Joel S. Schuman". Optical Coherence Tomography News. Retrieved 2015-08-29. "Sight + Sound" (PDF). ... invented the optical coherence tomography (OCT) technology. This technology, allows a quick and noninvasive 3D map of the eye, ... he is an inventor of optical coherence tomography (OCT), used world-wide for ocular diagnostics. Dr. Schuman has published more ...
Optical coherence tomography angiography (OCTA) is another noninvasive imaging technique that offers a detailed view of the ... Le, Patrick H.; Patel, Bhupendra C. (2023). "Optical Coherence Tomography Angiography". StatPearls. StatPearls Publishing. PMID ... Similarly, CSVD is typically recognized on both brain magnetic resonance imaging (MRI) and computed tomography (CT) scans, but ...
1991). "Optical Coherence Tomography" (PDF). Science. 254 (5035): 1178-81. Bibcode:1991Sci...254.1178H. doi:10.1126/science. ... Another application of the Michelson interferometer is in optical coherence tomography (OCT), a medical imaging technique using ... Fercher, A.F. (1996). "Optical Coherence Tomography" (PDF). Journal of Biomedical Optics. 1 (2): 157-173. Bibcode:1996JBO.....1 ... exceeds coherence length of light beams. The nontrivial features of phase fluctuations in optical phase-conjugating mirror had ...
Quantum optical coherence tomography (QOCT). Entangled-photon ellipsometry. Entangled-photon cryptography. Entangled-photon ... "Variations on the Theme of Quantum Optical Coherence Tomography: A Review" (PDF). Quantum Information Processing. 11 (4): 903- ... Optical engineers, 21st-century American physicists, Experimental physicists, Laser researchers, Quantum physicists, Optical ... Quantum Photonics: Optical heterodyne detection. Photon statistics and point processes. Single-photon detection at the retinal ...
Optical coherence tomography (OCT) is an imaging technique that utilizes low-coherence interferometry to generate high- ... "Optical coherence tomography: an emerging technology for biomedical imaging and optical biopsy". Neoplasia. 2 (1-2): 9-25. doi: ... Downsides of optical coherence tomography include limited depth penetration in highly scattering tissues and a lower resolution ... Anagnostakou V, Ughi GJ, Puri AS, Gounis MJ (October 2021). "Optical Coherence Tomography for Neurovascular Disorders". ...
In 2010 the company also acquired LightLab Imaging, a company that developed optical coherence tomography technology that helps ... The device uses fractional flow reserve for measuring intra-arterial pressure and optical coherence tomography technology, ... optical coherence tomography (OCT) imaging systems; structural heart repair products; and neurostimulation devices. The ...
"winner of Optical Coherence Tomography Award". 9 January 2011. Retrieved 11 September 2016. "Giovanni J. Ughi, PhD". Google ... is one of the inventors of multimodality optical coherence tomography (OCT) and Laser-induced fluorescence molecular imaging, ... "Automatic segmentation of in-vivo intra-coronary optical coherence tomography images to assess stent strut apposition and ... "Intravascular fibrin molecular imaging improves the detection of unhealed stents assessed by optical coherence tomography in ...
"NASA - Optical Coherence Tomography Technology Demonstration". www.nasa.gov. Retrieved 2018-10-13. "What's Next for Twins Study ... She has since been studying Spaceflight-Associated Neuro-Ocular Syndrome, and sent an optical coherence tomography scanner up ...
Optical Coherence Tomography in Cardiovascular Research. CRC Press. ISBN 978-0-415-38340-0. Sesana, Laura (2006). Colombia ...
Fercher, Adolf F.; Drexler, Wolfgang; Hitzenberger, Christoph K.; Lasser, Theo (2003). "Optical coherence tomography - ... at visible and infrared wavelengths List of types of interferometers Multiple satellite imaging Optical coherence tomography ... Optical intensity interferometry has been revived, measuring the width of giant stars using the optical instruments of the ... Optical Engineering. 43 (9): 2156-2167. Bibcode:2004OptEn..43.2156C. doi:10.1117/1.1779232. Monnier, J. D. (2003). "Optical ...
She completed her Ph.D. in biomedical engineering at Duke University in 2007, specialising in optical coherence tomography. Her ... Her research group develops new imaging devices and techniques based on optical coherence tomography, and developing point-of- ... Ellerbee, Audrey K. (2014-10-01). "Optical coherence tomography: Technology and applications". 2014 IEEE Photonics Conference. ... Her research in biomedical optics focuses on developing new imaging techniques and devices for optical coherence tomography and ...
MS patients show axonal loss in the retina and optic nerve, which can be measured by Optical coherence tomography or by ... 2007). "Optical coherence tomography and disease subtype in multiple sclerosis". Neurology. 69 (22): 2085-2092. doi:10.1093/ ... March 2009). "Optical coherence tomography differs in neuromyelitis optica compared with multiple sclerosis". Neurology. 72 (12 ... Evangelou, Nikos; Alrawashdeh, Omar S. M (2016). "Anatomy of the Retina and the Optic Nerve". Optical Coherence Tomography in ...
"Ultrahigh-resolution full-field optical coherence tomography". Applied Optics. 43 (14): 2874-2883. Bibcode:2004ApOpt..43.2874D ... The advantage of this design is its ability to compensate for chromatic dispersion and other optical aberrations. In the image ...
Abazari, Azin; Allam, Souha S.; Adamus, Grazyna; Ghazi, Nicola G. (2016-11-21). "Optical Coherence Tomography Findings in ...
Fractional flow reserve Intracoronary Optical Coherence Tomography Hector M. Garcia-Garcia, Bill D. Gogas, Patrick W. Serruys ... "Intracoronary Optical Coherence Tomography: A Comprehensive Review". JACC: Cardiovascular Interventions. 2 (11): 1035-1046. doi ...
Findings from optical coherence tomography were normal. Amsler grid test results were highly variable, and the locations of ...
"Balanced detection for spectral domain optical coherence tomography". Optics Express. 21 (16): 19280-19291. Bibcode:2013OExpr.. ... to the specularly reflected light that is assessed in more conventional imaging methods such as optical coherence tomography. ... Multiple scattering low coherence interferometry (ms/LCI) is an imaging technique that relies on analyzing multiply scattered ... As in traditional OCT, the beam interference coherence gates the light in order to filter out photons that have not traveled a ...
The optical contrast of gas vesicles also enables them to serve as contrast agents in optical coherence tomography, with ... "Biomolecular Contrast Agents for Optical Coherence Tomography" (PDF). bioRxiv. doi:10.1101/595157. S2CID 133072739. Shapiro MG ...
... where he has pioneered new optical imaging technologies in the fields of optical coherence tomography, multi-photon microscopy ... "CAREER: Functional Optical Coherence Tomography for Neural Imaging". www.nsf.gov. Retrieved 2017-12-12. "Hans Sigrist Prize ... 2011). "Handheld Optical Coherence Tomography Scanner for Primary Care Diagnostics". IEEE Trans. Biomed. Eng. 58 (3): 741-744. ... While at MIT, he was involved in the invention and early development of optical coherence tomography (OCT). Boppart started the ...
Optical coherence tomography (OCT) is an imaging technique that uses interferometry with short-coherence-length light to obtain ... Optical coherence tomography (OCT) is a technique for obtaining sub-surface images of translucent or opaque materials at a ... "optical coherence tomography". Since then, OCT with micrometer resolution and cross-sectional imaging capabilities has become a ... The optical setup typically consists of an interferometer (Fig. 1, typically Michelson type) with a low coherence, broad ...
Keyword:Optical Coherence Tomography. Papers. Multi-task Convolutional Neural Networks for the End-to-end Simultaneous ...
Optical Coherence Tomography Angiography - A Special Issue published by Hindawi ... Optical coherence tomography angiography (OCT A) is an emerging technology to image the vascular system of the eye. At present ... Optical Coherence Tomography Angiography of Combined Central Retinal Artery and Vein Occlusion. Shuo-chieh Wu , Victor M. ... Optical Coherence Tomography Angiography of Purtscher Retinopathy after Severe Traffic Accident in 16-Year-Old Boy. Hassan ...
Visible-light spectroscopic optical coherence tomography: applications and technology ... Visible-light spectroscopic optical coherence tomography: applications and technology. Visible-light spectroscopic optical ... Visible-light spectroscopic optical coherence tomography: applications and technology. Voor meer informatie zie de Engelse ... UTFaculteitenTNWEvenementenPromotie Carlos Cuartas Velez , Visible-light spectroscopic optical coherence tomography: ...
This piece of equipment is called 3D Optical Coherence Tomography system (3D OCT). ...
Relationship between optical coherence tomography retinal parameters and visual acuity in neovascular age-related macular ... Purpose: To investigate the relationship between optical coherence tomography (OCT)-derived measurements of retinal morphology ...
We present optical coherence tomography (OCT) with 2 nm axial resolution using broadband soft X-ray radiation (SXR) from a ... Optical coherence tomography using broad-bandwidth XUV and sof X-ray radiation. Appl. Phys. B 106, 789-795 (2012). ... Nanometer resolution optical coherence tomography using broad bandwidth XUV and soft x-ray radiation. Scientific Reports 6, ... Optical coherence tomography (OCT) with 2 nm axial resolution using a compact laser plasma soft X-ray source. *Przemysław ...
Title:Spectral Bandwidth Recovery of Optical Coherence Tomography Images using Deep Learning. Authors:Timothy T. Yu, Da Ma, ... Abstract:Optical coherence tomography (OCT) captures cross-sectional data and is used for the screening, monitoring, and ... Download a PDF of the paper titled Spectral Bandwidth Recovery of Optical Coherence Tomography Images using Deep Learning, by ... Download a PDF of the paper titled Spectral Bandwidth Recovery of Optical Coherence Tomography Images using Deep Learning, by ...
Zhang S, Wu C, Liu L, Jia Y, Zhang Y, Zhang Y, Zhang H, Zhong Y, Huang D (2017) Optical coherence tomography angiography of the ... Fu, L., Chan, Y.K., Fang, J. et al. Optical coherence tomography angiography of the macular microcirculation in acute primary ... Optical coherence tomography angiography (OCT-A) was performed to analyze the macular whole image vessel density (wiVD) and ... Optical coherence tomography angiography of the macular microcirculation in acute primary angle closure treated with ...
Optical coherence tomography to detect and manage retinal disease and glaucoma. Am J Ophthalmol 2004;137:156-69. ... Optical coherence tomography of cystoid macular edema associated with retinitis pigmentosa. Am J Ophthalmol 1999;128:185-91. ... Optical coherence tomography use in evaluation of the vitreoretinal interface: a review. Surv Ophthalmol 2007;52:397-421. ... Optical coherence tomography of idiopathic macular epiretinal membranes before and after surgery. Am J Ophthalmol 2000;130:732- ...
Bibliographic details on Choroid segmentation from Optical Coherence Tomography with graph-edge weights learned from deep ... Choroid segmentation from Optical Coherence Tomography with graph-edge weights learned from deep convolutional neural networks. ...
Optical Coherence Tomography Image IOD specifies a multi-frame image acquired on an Intravascular Optical Coherence Tomography ... A.66 Intravascular Optical Coherence Tomography Image IOD (Current) Prev A Composite Information Object Definitions (Normative) ... The Intravascular Optical Coherence Tomography Image IOD is used in two SOP Classes as defined in PS3.4 Storage Service Class, ... PS3.3 , Composite Information Object Definitions (Normative) , Intravascular Optical Coherence Tomography Image IOD ...
Aim To evaluate spectral domain optical coherence tomography (SD-OCT) changes in central retina and choroid in patients with ...
Hybrid Optical-Digital Coherence Tomography. For more information on the studentships and the application process, please visit ... Hybrid Optical-Digital Coherence Tomography. For more information on the studentships and the application process, please visit ...
... non-invasive skin imaging technology called line-field confocal optical coherence tomography (LC-OCT), which gives detailed 3D ...
Association of Cardiac Allograft Vasculopathy Plaque Characteristics by Optical Coherence Tomography With Coronary Physiology ...
... is an imaging technique that provides high resolution, non-destructive, real-time ... Optical Coherence Tomography (OCT) is an imaging technique that provides high resolution, non-destructive, in situ, real-time ... Variable Optical Delay Lines -small form factor. • Balanced Photodetectors - low noise. • K-Clock • Optical Vector Analyzer for ... Wideband Optical Couplers and Collimators. • Variable Optical Delay Lines. • Polarization Diverse Receiver. • Manufacturing and ...
Appendix 1. Optical coherence tomography (OCT) of the affected members showed the central loss of outer retina structure. ...
Real-Time optical coherence tomography of the anterior segment at 1310 nm. Arch Ophthalmol 2001;119:1179-85.doi:10.1001/ ... Anterior segment optical coherence tomography (AS-OCT) has been qualitatively applied for classification of plateau iris; ... Detection of primary angle closure using anterior segment optical coherence tomography in Asian eyes. Ophthalmology 2007;114:33 ... Deep learning for anterior segment optical coherence tomography to predict the presence of plateau iris. Transl Vis Sci Technol ...
Zhong, Jianfeng and Zhong, Shuncong and Zhang, Qiukun and Yao, Ligang (2015) Two-dimensional optical coherence tomography for ... Text. Filename: Zhong_etal_OLE_2015_Two_dimentional_optical_coherence_tomography_for_real_time.pdf Accepted Author Manuscript ... two-dimensional optical coherence tomography, absolute displacement measurement, response only modal analysis, Naval ... We present a two-dimensional optical coherence vibration tomography (2DOCVT) system with an ultra-precision displacement ...
Our goal was to evaluate the feasibility and potential role of bedside optical coherence tomography (OCT) in Tersons Syndrome ... Bedside Optical Coherence Tomography for Tersons Syndrome screening in Acute Subarachnoid Hemorrhage: A pilot study.. ... Enhanced depth imaging optical coherence tomography of optic nerve head drusen. Ophthalmology. 2013;120(7):1409-14. 6. ... Introduction: Our goal was to evaluate the feasibility and potential role of bedside optical coherence tomography (OCT) in ...
New principle for optical tomography and profilometry based on spatial coherence synthesis with a spatially modulated extended ... This function of longitudinal coherence control provides new possibilities in optical tomography and profilometry. Quantitative ... we generated a special optical field that exhibits high coherence selectively for the particular pair of points at the ... Giving a new physical interpretation to the principle of longitudinal coherence control, we propose an improved method for ...
Download a PDF of the paper titled Normalized Blood Flow Index in Optical Coherence Tomography Angiography Provides a Sensitive ... Download a PDF of the paper titled Normalized Blood Flow Index in Optical Coherence Tomography Angiography Provides a Sensitive ... Title:Normalized Blood Flow Index in Optical Coherence Tomography Angiography Provides a Sensitive Biomarker of Early Diabetic ... Optical coherence tomography angiography (OCTA) images of 30 eyes from 20 healthy controls, 21 eyes of diabetic patients with ...
Bioptigen (now part of Leica Microsystems) Optical Coherence Tomography (OCT) systems provide ophthalmologists with a gentle, ... which requires adding an optical connection without losing optical performance. ... In the end, a modular design (separate computing, optical, probe, and cart modules) met all the needs and resulted in a product ... Performance was maximized by a clever arrangement of the computing components to optimize cooling and by isolating the optical ...
... the performance of swept source optical coherence tomography (SS-OCT) has experienced an unprecedented improvement which is ... High-speed phase-stable swept source optical coherence tomography: functional imaging and biomedical applications. Ling, Yuye ... In the past decades, the performance of swept source optical coherence tomography (SS-OCT) has experienced an unprecedented ...
Keywords: Bevacizumab, retinal pigment epithelial tear, spectral domain optical coherence tomography. How to cite this article: ... CHOROIDAL NEOVASCULARIZATION ASSOCIATED WITH RETINAL PIGMENT EPITHELIAL TEAR IMAGED BY OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY ... 2],[3] Retracted RPE after the rip generates increased reflectivity on low-resolution optical coherence tomography (OCT). [4] ... Spectral domain optical coherence tomography features of multiple subfoveal retinal pigment epithelial tears after intravitreal ...
Optical coherence tomography angiography (OCTA) has significantly enhanced our knowledge of the retinal and inner choroidal ... AIM: To assess the macular capillary networks and foveal avascular zone (FAZ) with swept-source optical coherence tomography ... to a cross-sectional study using swept source optical coherence tomography angiography, which allows dense scanning of the ... according to a cross-sectional study using swept source optical coherence tomography angiography (SS OCTA) ...
A polarization-sensitive optical coherence tomography (PS-OCT) is a common approach to non-invasively imaging in biomedical ... A polarization-sensitive optical coherence tomography (PS-OCT) is a common approach to non-invasively imaging in biomedical ... Polarization-Sensitive Optical Coherence Tomography Using a Polarization-Insensitive Detector. Tech ID: 32080 / UC Case 2019- ...
Avhandling: Retinal ganglion cell examination with Optical Coherence Tomography reflects physiological and pathological changes ... Optical Coherence Tomography (OCT) is an accessible and easily operated clinical device that can provide a detailed image of ... Retinal ganglion cell examination with Optical Coherence Tomography reflects physiological and pathological changes in the eye ... Cost and benefits of cone beam computed tomography : for maxillary canines with eruption disturbance ...
Optical coherence tomography, ST-segment elevation myocardial infarction, Stent expansion Persistent URL doi.org/10.1007/s10554 ... Impact of optical coherence tomography findings on clinical outcomes in ST-segment elevation myocardial infarction patients: a ... Purpose: To investigate the association of the degree of stent expansion, as assessed by optical coherence tomography (OCT), ... Impact of optical coherence tomography findings on clinical outcomes in ST-segment elevation myocardial infarction patients: a ...
  • Optical coherence tomography angiography (OCT A) is an emerging technology to image the vascular system of the eye. (hindawi.com)
  • Optical coherence tomography angiography (OCT-A) was performed to analyze the macular whole image vessel density (wiVD) and parafoveal vessel density (pfVD). (springer.com)
  • Wang X, Jiang C, Kong X, Yu X, Sun X (2017) Peripapillary retinal vessel density in eyes with acute primary angle closure: an optical coherence tomography angiography study. (springer.com)
  • Purpose: To evaluate the sensitivity of normalized blood flow index (NBFI) for detecting early diabetic retinopathy (DR). Methods: Optical coherence tomography angiography (OCTA) images of 30 eyes from 20 healthy controls, 21 eyes of diabetic patients with no DR (NoDR) and 26 eyes from 22 patients with mild non-proliferative DR (NPDR) were analyzed in this study. (arxiv.org)
  • Our retina diagnostic testing procedures include retinal exams , fluorescein angiography, ICG angiography , optical coherence tomography , and ultrasound . (illinoisretina.com)
  • Optical coherence tomography and fluorescein angiography (FA) were performed before treatment and at subsequent follow-up examinations in all eyes. (qxmd.com)
  • Optical coherence tomography appears to be useful in monitoring the retinal changes that occur following PDT of CNV and may assist in understanding the changes observed on angiography. (qxmd.com)
  • Important aspects of workup regarding diabetic retinopathy include fasting glucose and hemoglobin A1c, fluorescein angiography, optical coherence tomography, and B-scan ultrasonography. (medscape.com)
  • This Section defines an Information Object to be used with Intravascular Optical Coherence Tomography imaging devices. (nema.org)
  • The Intravascular Optical Coherence Tomography Image IOD specifies a multi-frame image acquired on an Intravascular Optical Coherence Tomography modality. (nema.org)
  • The Intravascular Optical Coherence Tomography Image IOD is used in two SOP Classes as defined in PS3.4 Storage Service Class, a SOP Class for storage of images intended for presentation, and a SOP Class for storage of images intended for further processing before presentation. (nema.org)
  • Aim To evaluate spectral domain optical coherence tomography (SD-OCT) changes in central retina and choroid in patients with sickle cell disease (SCD). (bmj.com)
  • Optical coherence tomography (OCT) of the affected members showed the central loss of outer retina structure. (molvis.org)
  • The advanced diagnostic tool known as Optical Coherence Tomography (OCT) is a safe, non-contact, and non-invasive imaging technique that is commonly used by retina specialists to check on various aspects of vision health. (illinoisretina.com)
  • Optical Coherence Tomography uses light waves to take cross-section images of your retina, which is the area of light-sensitive cells at the back of your eye that is responsible for receiving light and transmitting it into messages that are sent up to the brain. (nfe2020.com)
  • Optical coherence tomography (OCT) uses light to generate a cross-sectional image of the retina. (medscape.com)
  • Short-coherence-length light can be obtained using a superluminescent diode (SLD) with a broad spectral bandwidth or a broadly tunable laser with narrow linewidth. (wikipedia.org)
  • The retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thicknesses were assessed using spectral-domain optical coherence tomography. (springer.com)
  • In this case report, we describe the occurrence of multiple RPE tears with the use of intravitreal bevacizumab and also correlate the preservation of visual acuity with features seen on spectral domain optical coherence tomography. (ijo.in)
  • Agreement between time-domain and spectral-domain optical coherence tomography in the assessment of macular thickness in patients with idiopathic macular telangiectasia type 2. (emmes.com)
  • To estimate the conversion factors to transpose macular thickness measurements on time-domain (TD) to various spectral-domain (SD) optical coherence tomography (OCT) machines in patients with macular telangiectasia type 2a (MacTel). (emmes.com)
  • To examine if racial differences in Bruch's membrane opening-minimum rim width (BMO-MRW) in spectral domain optical coherence tomography (SDOCT) exist, specifically between people of African descent (AD) and European descent (ED) in normal ocular health. (cdc.gov)
  • However, these preliminary BMO-MRW studies that generated normative databases have generally been performed in populations of European descent (ED). As the BMO-MRW parameter becomes more widely implemented in spectral-domain optical coherence tomography (SDOCT) through automated algorithms, it becomes necessary to understand how this parameter is affected by race. (cdc.gov)
  • dblp: Choroid segmentation from Optical Coherence Tomography with graph-edge weights learned from deep convolutional neural networks. (uni-trier.de)
  • To investigate the relationship between optical coherence tomography (OCT)-derived measurements of retinal morphology and visual acuity in patients with neovascular age-related macular degeneration (AMD). (nih.gov)
  • Optical coherence tomography findings following photodynamic therapy of choroidal neovascularization. (qxmd.com)
  • To develop an optical coherence tomography (OCT) classification system that monitors the response of eyes treated with photodynamic therapy (PDT) with verteporfin for subfoveal choroidal neovascularization (CNV) from age-related macular degeneration (AMD). (qxmd.com)
  • Tan O, Chopra V, Lu AT, Schuman JS, Ishikawa H, Wollstein G, Varma R, Huang D (2009) Detection of macular ganglion cell loss in glaucoma by Fourier-domain optical coherence tomography. (springer.com)
  • Optical coherence tomography (OCT) is an imaging technique that uses interferometry with short-coherence-length light to obtain micrometer-level depth resolution and uses transverse scanning of the light beam to form two- and three-dimensional images from light reflected from within biological tissue or other scattering media. (wikipedia.org)
  • In the decade preceding the invention of OCT, interferometry with short-coherence-length light had been investigated for a variety of applications. (wikipedia.org)
  • Optical coherence tomography (OCT) is an emerging noninvasive imaging technique, which is based on low-coherence interferometry. (escholarship.org)
  • OCT is an optical interferometry technique for acquiring cross-sectional images of tissue and other scattering materials with micrometer resolution. (ntt-review.jp)
  • Visible light optical coherence tomography (OCT) is emerging for spectroscopic and ultrahigh resolution imaging, but challenges remain. (escholarship.org)
  • The coherence parameters of the SXR radiation allowed for the OCT measurements of a bulk multilayer structure with 10 nm period and 40% bottom layer thickness to period ratio, with an axial resolution of about 2 nm and detect multilayer interfaces up to a depth of about 100 nm. (nature.com)
  • In the paper, detailed information about the source, its optimization, the optical system, OCT measurements and the results are presented and discussed. (nature.com)
  • Loewen NA, Xinbo Zhang O, Tan BA, Francis DS, Greenfield JS, Schuman RV, Huang D (2015) Combining measurements from three anatomical areas for glaucoma diagnosis using Fourier-domain optical coherence tomography. (springer.com)
  • Optical Coherence Tomography (OCT) is an accessible and easily operated clinical device that can provide a detailed image of this layer at a few micrometers level of precision in measurements. (avhandlingar.se)
  • Association between Optical Coherence Tomography Measurements and Clinical Parameters in Idiopathic Intracranial Hypertension. (bvsalud.org)
  • To correlate optical coherence tomography (OCT) measurements with clinical parameters in idiopathic intracranial hypertension (IIH). (bvsalud.org)
  • The higher speed allowed for 3-dimensional imaging, which can be visualized in both en face and cross-sectional views. (wikipedia.org)
  • Optical coherence tomography (OCT) captures cross-sectional data and is used for the screening, monitoring, and treatment planning of retinal diseases. (arxiv.org)
  • Optical coherence tomography (OCT) using a swept light source can acquire cross-sectional images of tissue with micrometer resolution for biomedical applications. (ntt-review.jp)
  • The retinal disease screening study: prospective comparison of nonmydriatic fundus photography and optical coherence tomography for detection of retinal irregularities. (cns.org)
  • The duplication of studies on this subject would provide a pediatric database grouping values on the peripapillary optical fiber thickness. (scitechnol.com)
  • However, since the introduction of optical coherence tomography (OCT) in 1991, it has become an invaluable tool in the diagnosis and management of different retinal disorders including ME. (bmj.com)
  • We present a two-dimensional optical coherence vibration tomography (2DOCVT) system with an ultra-precision displacement resolution of ~0.1 nm that is capable of in site real-time absolute displacement measurement of structural line vibrations. (strath.ac.uk)
  • two-dimensional optical coherence tomography, absolute displacement measurement, response only modal analysis, Naval architecture. (strath.ac.uk)
  • The article introduced the term "OCT" to credit its derivation from optical coherence-domain reflectometry, in which the axial resolution is based on temporal coherence. (wikipedia.org)
  • The optical coherence tomography (OCT) is part of the detection and monitoring of many retinal and optic nerve diseases. (scitechnol.com)
  • Purpose: To investigate the association of the degree of stent expansion, as assessed by optical coherence tomography (OCT), following stent implantation, and clinical outcomes in ST-segment elevation myocardial infarction (STEMI) patients. (eur.nl)
  • Optical coherence tomography study of healing characteristics of paclitaxel-eluting balloons vs. everolimus-eluting stents for in-stent restenosis: the SEDUCE (Safety and Efficacy of a Drug elUting balloon in Coronary artery rEstenosis) randomised clinical trial. (umassmed.edu)
  • Classification results across frames displayed in en face view matched closely to annotated counterparts. (supercomputing.org)
  • Optical coherence tomography findings were evaluated and compared with corresponding FA. (qxmd.com)
  • OCT is similar to the technology associated with computed tomography (CT) scans of internal organs. (illinoisretina.com)
  • Why are Optical Coherence Tomography scans important? (nfe2020.com)
  • In the current study, researchers found that using a new, non-invasive skin imaging technology called line-field confocal optical coherence tomography (LC-OCT), which gives detailed 3D images at cellular level, significantly increased diagnostic accuracy. (hospitalhealthcare.com)
  • Bioptigen (now part of Leica Microsystems ) Optical Coherence Tomography (OCT) systems provide ophthalmologists with a gentle, contact-free solution to quickly create real-time, high-definition 3D images of eye tissue that is easy on patients and captures the right data the first time, every time. (porticos.net)
  • This piece of equipment is called 3D Optical Coherence Tomography system (3D OCT). (selectspecs.com)
  • Remove/replace the probe from the central unit (hardwired in current system), which requires adding an optical connection without losing optical performance. (porticos.net)
  • Visual system function and structure were assessed for 8 weeks after exposure using optokinetic nystagmus and optical coherence tomography. (cdc.gov)
  • The heart of the book covers the essential topics of tissue optics, as well as optical imaging system design concepts. (lu.se)
  • Bedside Optical Coherence Tomography for Terson's Syndrome screening in Acute Subarachnoid Hemorrhage: A pilot study. (cns.org)
  • Our goal was to evaluate the feasibility and potential role of bedside optical coherence tomography (OCT) in Terson's Syndrome (TS) in patients with acute subarachnoid hemorrhage (aSAH) and its potential role in blindness prevention. (cns.org)
  • The cavity consists of a 1.3-μm semiconductor optical amplifier (SOA) module, a collimator, a KTN deflector with electrodes, a cylindrical concave lens, a grating, and a high reflector (HR). The SOA module has a 10% reflector coupled to an optical fiber through an optical isolator on one side. (ntt-review.jp)
  • Katia Del Rio-Tsonis, Ph.D., of Miami University, Ohio, uses a 3D imaging technology called optical coherence tomography (OCT) to watch newts' lenses regenerate. (medlineplus.gov)
  • Optical coherence tomography (OCT) is a non-contact, diagnostic method that uses infrared light, which allows the analysis of the retinal structure by means of high-resolution tomographic cross sections. (bmj.com)
  • A polarization-sensitive optical coherence tomography (PS-OCT) is a common approach to non-invasively imaging in biomedical applications. (universityofcalifornia.edu)
  • Optical coherence tomography (OCT) has attracted attention because of its potential use as a medical imaging technology [1]. (ntt-review.jp)
  • The computational approach to image acquisition and analysis plays an important role in medical imaging and optical coherence tomography (OCT). This thesis is dedicated to the development and evaluation of algorithmic solutions for better image acquisition and analysis with a focus on OCT retinal imaging. (kent.ac.uk)
  • Marginal analysis of resin composite restorative systems using optical coherence tomography. (bvsalud.org)
  • Optical coherence tomography (OCT) allows one to image an internal structure of the investigated sample in a noninvasive and nondestructive way 1 . (nature.com)
  • We advance studies of subretinal treatments by developing a microscope-integrated optical coherence tomography (MIOCT) image-based method for measuring the volume of therapeutics delivered into the subretinal space. (arvojournals.org)
  • Optical Coherence Tomography is a non-invasive imaging test that may be performed as a standard part of your regular, comprehensive exams, or you may be able to request this test as an addition to your usual exam. (nfe2020.com)
  • Optical Coherence Tomography (OCT) is an imaging technique that provides high resolution, non-destructive, in situ, real-time reflectivity profiling of non-absorptive samples. (teracomm.com)
  • Optical super-resolution microscopy of molecular mechanisms of disease. (lu.se)
  • Giving a new physical interpretation to the principle of longitudinal coherence control, we propose an improved method for synthesizing a desired spatial coherence function along the longitudinal axis of light propagation. (spie.org)
  • By controlling the irradiance of an extended quasi-monochromatic spatially incoherent source with a spatial light modulator, we generated a special optical field that exhibits high coherence selectively for the particular pair of points at the specified locations along the axis of beam propagation. (spie.org)
  • In the end, a modular design (separate computing, optical, probe, and cart modules) met all the needs and resulted in a product with more functionality, practicality, and appeal. (porticos.net)
  • Interferometric reflectometry of biological tissue, especially of the human eye using short-coherence-length light (also referred to as partially-coherent, low-coherence, or broadband, broad-spectrum, or white light) was investigated in parallel by multiple groups worldwide since 1980s. (wikipedia.org)
  • After the fundamentals of photon transport in biological tissues are established, various optical imaging techniques for biological tissues are covered. (lu.se)
  • Performance was maximized by a clever arrangement of the computing components to optimize cooling and by isolating the optical components. (porticos.net)