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.
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).
Evoked Potentials, Visual
The electric response evoked in the cerebral cortex by visual stimulation or stimulation of the visual pathways.
The total area or space visible in a person's peripheral vision with the eye looking straightforward.
Area of the OCCIPITAL LOBE concerned with the processing of visual information relayed via VISUAL PATHWAYS.
A nonspecific term referring to impaired vision. Major subcategories include stimulus deprivation-induced amblyopia and toxic amblyopia. Stimulus deprivation-induced amblyopia is a developmental disorder of the visual cortex. A discrepancy between visual information received by the visual cortex from each eye results in abnormal cortical development. STRABISMUS and REFRACTIVE ERRORS may cause this condition. Toxic amblyopia is a disorder of the OPTIC NERVE which is associated with ALCOHOLISM, tobacco SMOKING, and other toxins and as an adverse effect of the use of some medications.
Set of cell bodies and nerve fibers conducting impulses from the eyes to the cerebral cortex. It includes the RETINA; OPTIC NERVE; optic tract; and geniculocalcarine tract.
The removal of a cataractous CRYSTALLINE LENS from the eye.
Deviations from the average or standard indices of refraction of the eye through its dioptric or refractive apparatus.
Vision considered to be inferior to normal vision as represented by accepted standards of acuity, field of vision, or motility. Low vision generally refers to visual disorders that are caused by diseases that cannot be corrected by refraction (e.g., MACULAR DEGENERATION; RETINITIS PIGMENTOSA; DIABETIC RETINOPATHY, etc.).
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.
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)
The ability to detect sharp boundaries (stimuli) and to detect slight changes in luminance at regions without distinct contours. Psychophysical measurements of this visual function are used to evaluate visual acuity and to detect eye disease.
The process in which light signals are transformed by the PHOTORECEPTOR CELLS into electrical signals which can then be transmitted to the brain.
Application of tests and examinations to identify visual defects or vision disorders occurring in specific populations, as in school children, the elderly, etc. It is differentiated from VISION TESTS, which are given to evaluate/measure individual visual performance not related to a specific population.
The inability to see or the loss or absence of perception of visual stimuli. This condition may be the result of EYE DISEASES; OPTIC NERVE DISEASES; OPTIC CHIASM diseases; or BRAIN DISEASES affecting the VISUAL PATHWAYS or OCCIPITAL LOBE.
Tomography, Optical Coherence
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)
Visually Impaired Persons
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)
Visual Field Tests
Method of measuring and mapping the scope of vision, from central to peripheral of each eye.
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.
Misalignment of the visual axes of the eyes. In comitant strabismus the degree of ocular misalignment does not vary with the direction of gaze. In noncomitant strabismus the degree of misalignment varies depending on direction of gaze or which eye is fixating on the target. (Miller, Walsh & Hoyt's Clinical Neuro-Ophthalmology, 4th ed, p641)
Pattern Recognition, Visual
Unequal curvature of the refractive surfaces of the eye. Thus a point source of light cannot be brought to a point focus on the retina but is spread over a more or less diffuse area. This results from the radius of curvature in one plane being longer or shorter than the radius at right angles to it. (Dorland, 27th ed)
Lens Implantation, Intraocular
Insertion of an artificial lens to replace the natural CRYSTALLINE LENS after CATARACT EXTRACTION or to supplement the natural lens which is left in place.
Damage or trauma inflicted to the eye by external means. The concept includes both surface injuries and intraocular injuries.
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).
Investigative technique commonly used during ELECTROENCEPHALOGRAPHY in which a series of bright light flashes or visual patterns are used to elicit brain activity.
Diseases affecting the eye.
The administration of substances into the VITREOUS BODY of the eye with a hypodermic syringe.
The use of green light-producing LASERS to stop bleeding. The green light is selectively absorbed by HEMOGLOBIN, thus triggering BLOOD COAGULATION.
The blending of separate images seen by each eye into one composite image.
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.
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)
Artificial implanted lenses.
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.
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.
Relatively bright light, or the dazzling sensation of relatively bright light, which produces unpleasantness or discomfort, or which interferes with optimal VISION, OCULAR. (Cline et al., Dictionary of Visual Science, 4th ed)
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 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)
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.
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.
Images seen by one eye.
Retinal Vein Occlusion
A pathological process consisting of the formation of new blood vessels in the CHOROID.
Nystagmus present at birth or caused by lesions sustained in utero or at the time of birth. It is usually pendular, and is associated with ALBINISM and conditions characterized by early loss of central vision. Inheritance patterns may be X-linked, autosomal dominant, or recessive. (Adams et al., Principles of Neurology, 6th ed, p275)
Involuntary movements of the eye that are divided into two types, jerk and pendular. Jerk nystagmus has a slow phase in one direction followed by a corrective fast phase in the opposite direction, and is usually caused by central or peripheral vestibular dysfunction. Pendular nystagmus features oscillations that are of equal velocity in both directions and this condition is often associated with visual loss early in life. (Adams et al., Principles of Neurology, 6th ed, p272)
Diseases of the 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.
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.
Color Vision Defects
Defects of color vision are mainly hereditary traits but can be secondary to acquired or developmental abnormalities in the CONES (RETINA). Severity of hereditary defects of color vision depends on the degree of mutation of the ROD OPSINS genes (on X CHROMOSOME and CHROMOSOME 3) that code the photopigments for red, green and blue.
Partial or total replacement of all layers of a central portion of the cornea.
Keratomileusis, Laser In Situ
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.
Ophthalmologic Surgical Procedures
Surgery performed on the eye or any of its parts.
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.
The aperture in the iris through which light passes.
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)
Agents that dilate the pupil. They may be either sympathomimetics or parasympatholytics.
The positioning and accommodation of eyes that allows the image to be brought into place on the FOVEA CENTRALIS of each eye.
A surgical specialty concerned with the structure and function of the eye and the medical and surgical treatment of its defects and diseases.
Gas lasers with excited dimers (i.e., excimers) as the active medium. The most commonly used are rare gas monohalides (e.g., argon fluoride, xenon chloride). Their principal emission wavelengths are in the ultraviolet range and depend on the monohalide used (e.g., 193 nm for ArF, 308 nm for Xe Cl). These lasers are operated in pulsed and Q-switched modes and used in photoablative decomposition involving actual removal of tissue. (UMDNS, 2005)
Examination of the interior of the eye with an ophthalmoscope.
Hemorrhage into the VITREOUS BODY.
Voluntary or reflex-controlled movements of the eye.
A refractive error in which rays of light entering the eye parallel to the optic axis are brought to a focus behind the retina, as a result of the eyeball being too short from front to back. It is also called farsightedness because the near point is more distant than it is in emmetropia with an equal amplitude of accommodation. (Dorland, 27th ed)
A type of refractive surgery of the CORNEA to correct MYOPIA and ASTIGMATISM. An EXCIMER LASER is used directly on the surface of the EYE to remove some of the CORNEAL EPITHELIUM thus reshaping the anterior curvature of the cornea.
The administration of substances into the eye with a hypodermic syringe.
An operation for retinal detachment which reduces the size of the globe by indenting the sclera so that it approximates the retina.
Disorder occurring in the central or peripheral area of the cornea. The usual degree of transparency becomes relatively opaque.
Suppurative inflammation of the tissues of the internal structures of the eye frequently associated with an infection.
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.
Presence of an intraocular lens after cataract extraction.
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.
Bleeding from the vessels of the retina.
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)
Corneal Wavefront Aberration
Descemet Stripping Endothelial Keratoplasty
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.
Wet Macular Degeneration
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.
Disorders of the choroid including hereditary choroidal diseases, neoplasms, and other abnormalities of the vascular layer of the uvea.
Retinal Photoreceptor Cell Inner Segment
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.
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).
The pressure of the fluids in the eye.
The dioptric adjustment of the EYE (to attain maximal sharpness of retinal imagery for an object of regard) referring to the ability, to the mechanism, or to the process. Ocular accommodation is the effecting of refractive changes by changes in the shape of the CRYSTALLINE LENS. Loosely, it refers to ocular adjustments for VISION, OCULAR at various distances. (Cline et al., Dictionary of Visual Science, 4th ed)
Retinal Artery Occlusion
Retinal Photoreceptor Cell Outer Segment
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.
The coagulation of tissue by an intense beam of light, including laser (LASER COAGULATION). In the eye it is used in the treatment of retinal detachments, retinal holes, aneurysms, hemorrhages, and malignant and benign neoplasms. (Dictionary of Visual Science, 3d ed)
Central Serous Chorioretinopathy
A visual impairment characterized by the accumulation of fluid under the retina through a defect in the retinal pigment epithelium.
Ocular Physiological Phenomena
Processes and properties of the EYE as a whole or of any of its parts.
Eye Infections, Fungal
Infection by a variety of fungi, usually through four possible mechanisms: superficial infection producing conjunctivitis, keratitis, or lacrimal obstruction; extension of infection from neighboring structures - skin, paranasal sinuses, nasopharynx; direct introduction during surgery or accidental penetrating trauma; or via the blood or lymphatic routes in patients with underlying mycoses.
Artificial device such as an externally-worn camera attached to a stimulator on the RETINA, OPTIC NERVE, or VISUAL CORTEX, intended to restore or amplify vision.
Optic Nerve Diseases
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.
Inflammation of the choroid as well as the retina and vitreous body. Some form of visual disturbance is usually present. The most important characteristics of posterior uveitis are vitreous opacities, choroiditis, and chorioretinitis.
Color Perception Tests
Type of vision test used to determine COLOR VISION DEFECTS.
Loss of epithelial tissue from the surface of the cornea due to progressive erosion and necrosis of the tissue; usually caused by bacterial, fungal, or viral infection.
Diagnostic Techniques, Ophthalmological
Methods and procedures for the diagnosis of diseases of the eye or of vision disorders.
Adjustment of the eyes under conditions of low light. The sensitivity of the eye to light is increased during dark adaptation.
Eye Foreign Bodies
Inanimate objects that become enclosed in the eye.
Optic Nerve Neoplasms
Benign and malignant neoplasms that arise from the optic nerve or its sheath. OPTIC NERVE GLIOMA is the most common histologic type. Optic nerve neoplasms tend to cause unilateral visual loss and an afferent pupillary defect and may spread via neural pathways to the brain.
Partial or total replacement of the CORNEA from one human or animal to another.
Function of the human eye that is used in bright illumination or in daylight (at photopic intensities). Photopic vision is performed by the three types of RETINAL CONE PHOTORECEPTORS with varied peak absorption wavelengths in the color spectrum (from violet to red, 400 - 700 nm).
Incomplete rupture of the zonule with the displaced lens remaining behind the pupil. In dislocation, or complete rupture, the lens is displaced forward into the anterior chamber or backward into the vitreous body. When congenital, this condition is known as ECTOPIA LENTIS.
Retinal Cone Photoreceptor Cells
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.
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)
Bleeding in the anterior chamber of the eye.
Organic siloxanes which are polymerized to the oily stage. The oils have low surface tension and density less than 1. They are used in industrial applications and in the treatment of retinal detachment, complicated by proliferative vitreoretinopathy.
Albinism affecting the eye in which pigment of the hair and skin is normal or only slightly diluted. The classic type is X-linked (Nettleship-Falls), but an autosomal recessive form also exists. Ocular abnormalities may include reduced pigmentation of the iris, nystagmus, photophobia, strabismus, and decreased visual acuity.
The functional superiority and preferential use of one eye over the other. The term is usually applied to superiority in sighting (VISUAL PERCEPTION) or motor task but not difference in VISUAL ACUITY or dysfunction of one of the eyes. Ocular dominance can be modified by visual input and NEUROTROPHIC FACTORS.
A form of ocular misalignment characterized by an excessive convergence of the visual axes, resulting in a "cross-eye" appearance. An example of this condition occurs when paralysis of the lateral rectus muscle causes an abnormal inward deviation of one eye on attempted gaze.
Antibodies, Monoclonal, Humanized
Antibodies from non-human species whose protein sequences have been modified to make them nearly identical with human antibodies. If the constant region and part of the variable region are replaced, they are called humanized. If only the constant region is modified they are called chimeric. INN names for humanized antibodies end in -zumab.
Recording of the average amplitude of the resting potential arising between the cornea and the retina in light and dark adaptation as the eyes turn a standard distance to the right and the left. The increase in potential with light adaptation is used to evaluate the condition of the retinal pigment epithelium.
Eye Infections, Bacterial
Infections in the inner or external eye caused by microorganisms belonging to several families of bacteria. Some of the more common genera found are Haemophilus, Neisseria, Staphylococcus, Streptococcus, and Chlamydia.
The organ of sight constituting a pair of globular organs made up of a three-layered roughly spherical structure specialized for receiving and responding to light.
A glucocorticoid derivative used topically in the treatment of various skin disorders. It is usually employed as a cream, gel, lotion, or ointment. It has also been used topically in the treatment of inflammatory eye, ear, and nose disorders. (From Martindale, The Extra Pharmacopoeia, 30th ed, p732)
A procedure to surgically correct REFRACTIVE ERRORS by cutting radial slits into the CORNEA to change its refractive properties.
Sterile solutions that are intended for instillation into the eye. It does not include solutions for cleaning eyeglasses or CONTACT LENS SOLUTIONS.
Absence of crystalline lens totally or partially from field of vision, from any cause except after cataract extraction. Aphakia is mainly congenital or as result of LENS DISLOCATION AND SUBLUXATION.
Absence of the crystalline lens resulting from cataract extraction.
Magnetic Resonance Imaging
Partial or complete loss of vision in one half of the visual field(s) of one or both eyes. Subtypes include altitudinal hemianopsia, characterized by a visual defect above or below the horizontal meridian of the visual field. Homonymous hemianopsia refers to a visual defect that affects both eyes equally, and occurs either to the left or right of the midline of the visual field. Binasal hemianopsia consists of loss of vision in the nasal hemifields of both eyes. Bitemporal hemianopsia is the bilateral loss of vision in the temporal fields. Quadrantanopsia refers to loss of vision in one quarter of the visual field in one or both eyes.
Exudates and Transudates
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.
Lens Capsule, Crystalline
The surgical removal of the eyeball leaving the eye muscles and remaining orbital contents intact.
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.
Inflammation in which both the anterior and posterior segments of the uvea are involved and a specific focus is not apparent. It is often severe and extensive and a serious threat to vision. Causes include systemic diseases such as tuberculosis, sarcoidosis, and syphilis, as well as malignancies. The intermediate segment of the eye is not involved.
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.
Reproducibility of Results
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.
A group of CORTICOSTEROIDS that affect carbohydrate metabolism (GLUCONEOGENESIS, liver glycogen deposition, elevation of BLOOD SUGAR), inhibit ADRENOCORTICOTROPIC HORMONE secretion, and possess pronounced anti-inflammatory activity. They also play a role in fat and protein metabolism, maintenance of arterial blood pressure, alteration of the connective tissue response to injury, reduction in the number of circulating lymphocytes, and functioning of the central nervous system.
The point or frequency at which all flicker of an intermittent light stimulus disappears.
Method of making images on a sensitized surface by exposure to light or other radiant energy.
Optic Nerve Glioma
Glial cell derived tumors arising from the optic nerve, usually presenting in childhood.
Optic Neuropathy, Ischemic
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)
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.
Abnormal sensitivity to light. This may occur as a manifestation of EYE DISEASES; MIGRAINE; SUBARACHNOID HEMORRHAGE; MENINGITIS; and other disorders. Photophobia may also occur in association with DEPRESSION and other MENTAL DISORDERS.
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).
Photosensitive protein complexes of varied light absorption properties which are expressed in the PHOTORECEPTOR CELLS. They are OPSINS conjugated with VITAMIN A-based chromophores. Chromophores capture photons of light, leading to the activation of opsins and a biochemical cascade that ultimately excites the photoreceptor cells.
An excessive amount of fluid in the cornea due to damage of the epithelium or endothelium causing decreased visual acuity.
Eye Diseases, Hereditary
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 abrupt voluntary shift in ocular fixation from one point to another, as occurs in reading.
Retinal Ganglion Cells
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.
Inflammation of the cornea.
Therapy using oral or topical photosensitizing agents with subsequent exposure to light.
Failure or imperfection of vision at night or in dim light, with good vision only on bright days. (Dorland, 27th ed)