A measurement of the thickness of the carotid artery walls. It is measured by B-mode ULTRASONOGRAPHY and is used as a surrogate marker for ATHEROSCLEROSIS.

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.

The measurement of subcutaneous fat located directly beneath the skin by grasping a fold of skin and subcutaneous fat between the thumb and forefinger and pulling it away from the underlying muscle tissue. The thickness of the double layer of skin and subcutaneous tissue is then read with a caliper. The five most frequently measured sites are the upper arm, below the scapula, above the hip bone, the abdomen, and the thigh. Its application is the determination of relative fatness, of changes in physical conditioning programs, and of the percentage of body fat in desirable body weight. (From McArdle, et al., Exercise Physiology, 2d ed, p496-8)

The middle layer of blood vessel walls, composed principally of thin, cylindrical, smooth muscle cells and elastic tissue. It accounts for the bulk of the wall of most arteries. The smooth muscle cells are arranged in circular layers around the vessel, and the thickness of the coat varies with the size of the vessel.

The innermost layer of an artery or vein, made up of one layer of endothelial cells and supported by an internal elastic lamina.

Either of the two principal arteries on both sides of the neck that supply blood to the head and neck; each divides into two branches, the internal carotid artery and the external carotid artery.

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.

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)

The two principal arteries supplying the structures of the head and neck. They ascend in the neck, one on each side, and at the level of the upper border of the thyroid cartilage, each divides into two branches, the external (CAROTID ARTERY, EXTERNAL) and internal (CAROTID ARTERY, INTERNAL) carotid arteries.

Methods and procedures for the diagnosis of diseases of the eye or of vision disorders.

Pathological conditions involving the CAROTID ARTERIES, including the common, internal, and external carotid arteries. ATHEROSCLEROSIS and TRAUMA are relatively frequent causes of carotid artery pathology.

Measurements of the height, weight, length, area, etc., of the human and animal body or its parts.

Provision of physical and biological barriers to the dissemination of potentially hazardous biologically active agents (bacteria, viruses, recombinant DNA, etc.). Physical containment involves the use of special equipment, facilities, and procedures to prevent the escape of the agent. Biological containment includes use of immune personnel and the selection of agents and hosts that will minimize the risk should the agent escape the containment facility.

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.

Measurement of the thickness of the CORNEA.

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.

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.

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).

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.

The thin, highly vascular membrane covering most of the posterior of the eye between the RETINA and SCLERA.

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)

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)

2,3-Diphosphoglycerate (2,3-DPG) is a physiological modulator of hemoglobin oxygen affinity, reducing its attraction to oxygen in red blood cells, which facilitates the release of oxygen to tissues with lower oxygen concentrations.

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.

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.

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 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 technique that deals with the measurement of the size, weight, and proportions of the human or other primate body.

The distance between the anterior and posterior poles of the eye, measured either by ULTRASONOGRAPHY or by partial coherence interferometry.

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)

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 ocular tension (INTRAOCULAR PRESSURE) with a tonometer. (Cline, et al., Dictionary of Visual Science, 4th ed)

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.

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.

The measurement of an organ in volume, mass, or heaviness.

A thickening and loss of elasticity of the walls of ARTERIES that occurs with formation of ATHEROSCLEROTIC PLAQUES within the ARTERIAL INTIMA.

Imaging methods that result in sharp images of objects located on a chosen plane and blurred images located above or below the plane.

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)

The lamellated connective tissue constituting the thickest layer of the cornea between the Bowman and Descemet membranes.

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.

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).

An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.

The visualization of deep structures of the body by recording the reflections or echoes of ultrasonic pulses directed into the tissues. Use of ultrasound for imaging or diagnostic purposes employs frequencies ranging from 1.6 to 10 megahertz.

The relative amounts of various components in the body, such as percentage of body fat.

A protective layer of firm, flexible cartilage over the articulating ends of bones. It provides a smooth surface for joint movement, protecting the ends of long bones from wear at points of contact.

Elements of limited time intervals, contributing to particular results or situations.

Examination of the interior of the eye with an ophthalmoscope.

Ultrasonic recording of the size, motion, and composition of the heart and surrounding tissues. The standard approach is transthoracic.

Enlargement of the LEFT VENTRICLE of the heart. This increase in ventricular mass is attributed to sustained abnormal pressure or volume loads and is a contributor to cardiovascular morbidity and mortality.

The use of statistical and mathematical methods to analyze biological observations and phenomena.

Refraction of LIGHT effected by the media of the EYE.

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 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.

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.

An excessive amount of fluid in the cornea due to damage of the epithelium or endothelium causing decreased visual acuity.

Method of measuring and mapping the scope of vision, from central to peripheral of each eye.

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 gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.

Thickening and loss of elasticity of the walls of ARTERIES of all sizes. There are many forms classified by the types of lesions and arteries involved, such as ATHEROSCLEROSIS with fatty lesions in the ARTERIAL INTIMA of medium and large muscular arteries.

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 total area or space visible in a person's peripheral vision with the eye looking straightforward.

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.

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.

A purely physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion; expressed quantitatively in units of force per unit area.

Specialized connective tissue composed of fat cells (ADIPOCYTES). It is the site of stored FATS, usually in the form of TRIGLYCERIDES. In mammals, there are two types of adipose tissue, the WHITE FAT and the BROWN FAT. Their relative distributions vary in different species with most adipose tissue being white.

The longest and largest bone of the skeleton, it is situated between the hip and the knee.

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.

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.

The thin layer of GRAY MATTER on the surface of the CEREBRAL HEMISPHERES that develops from the TELENCEPHALON and folds into gyri and sulchi. It reaches its highest development in humans and is responsible for intellectual faculties and higher mental functions.

A condition in which the intraocular pressure is elevated above normal and which may lead to glaucoma.

The mucous membrane lining of the uterine cavity that is hormonally responsive during the MENSTRUAL CYCLE and PREGNANCY. The endometrium undergoes cyclic changes that characterize MENSTRUATION. After successful FERTILIZATION, it serves to sustain the developing embryo.

A disease of the horny parts and of the adjacent soft structures of the feet of cattle, swine, and sheep. It is usually caused by Corynebacterium pyogenes or Bacteroides nodosus (see DICHELOBACTER NODOSUS). It is also known as interdigital necrobacillosis. (From Black's Veterinary Dictionary, 18th ed)

A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.

The mass or quantity of heaviness of an individual. It is expressed by units of pounds or kilograms.

Examination of the angle of the anterior chamber of the eye with a specialized optical instrument (gonioscope) or a contact prism lens.

The testing of materials and devices, especially those used for PROSTHESES AND IMPLANTS; SUTURES; TISSUE ADHESIVES; etc., for hardness, strength, durability, safety, efficacy, and biocompatibility.

Resistance and recovery from distortion of shape.

Characteristics or attributes of the outer boundaries of objects, including molecules.

Procedures for finding the mathematical function which best describes the relationship between a dependent variable and one or more independent variables. In linear regression (see LINEAR MODELS) the relationship is constrained to be a straight line and LEAST-SQUARES ANALYSIS is used to determine the best fit. In logistic regression (see LOGISTIC MODELS) the dependent variable is qualitative rather than continuously variable and LIKELIHOOD FUNCTIONS are used to find the best relationship. In multiple regression, the dependent variable is considered to depend on more than a single independent variable.

The properties, processes, and behavior of biological systems under the action of mechanical forces.

A malignant neoplasm derived from cells that are capable of forming melanin, which may occur in the skin of any part of the body, in the eye, or, rarely, in the mucous membranes of the genitalia, anus, oral cavity, or other sites. It occurs mostly in adults and may originate de novo or from a pigmented nevus or malignant lentigo. Melanomas frequently metastasize widely, and the regional lymph nodes, liver, lungs, and brain are likely to be involved. The incidence of malignant skin melanomas is rising rapidly in all parts of the world. (Stedman, 25th ed; from Rook et al., Textbook of Dermatology, 4th ed, p2445)

The industry concerned with processing, preparing, preserving, distributing, and serving of foods and beverages.

The lower right and left chambers of the heart. The right ventricle pumps venous BLOOD into the LUNGS and the left ventricle pumps oxygenated blood into the systemic arterial circulation.

PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.

The worsening of a disease over time. This concept is most often used for chronic and incurable diseases where the stage of the disease is an important determinant of therapy and prognosis.

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)

A prenatal ultrasonography measurement of the soft tissue behind the fetal neck. Either the translucent area below the skin in the back of the fetal neck (nuchal translucency) or the distance between occipital bone to the outer skin line (nuchal fold) is measured.

Statistical models in which the value of a parameter for a given value of a factor is assumed to be equal to a + bx, where a and b are constants. The models predict a linear regression.

Studies which start with the identification of persons with a disease of interest and a control (comparison, referent) group without the disease. The relationship of an attribute to the disease is examined by comparing diseased and non-diseased persons with regard to the frequency or levels of the attribute in each group.

Age as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or the effect of a circumstance. It is used with human or animal concepts but should be differentiated from AGING, a physiological process, and TIME FACTORS which refers only to the passage of time.

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 part of a human or animal body connecting the HEAD to the rest of the body.

Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.

The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.

Tumors or cancer of the SKIN.

Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons. Although SCANNING TRANSMISSION ELECTRON MICROSCOPY also scans the specimen point by point with the electron beam, the image is constructed by detecting the electrons, or their interaction products that are transmitted through the sample plane, so that is a form of TRANSMISSION ELECTRON MICROSCOPY.

The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.

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)

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.

A form of CARDIAC MUSCLE disease, characterized by left and/or right ventricular hypertrophy (HYPERTROPHY, LEFT VENTRICULAR; HYPERTROPHY, RIGHT VENTRICULAR), frequent asymmetrical involvement of the HEART SEPTUM, and normal or reduced left ventricular volume. Risk factors include HYPERTENSION; AORTIC STENOSIS; and gene MUTATION; (FAMILIAL HYPERTROPHIC CARDIOMYOPATHY).

Any of various animals that constitute the family Suidae and comprise stout-bodied, short-legged omnivorous mammals with thick skin, usually covered with coarse bristles, a rather long mobile snout, and small tail. Included are the genera Babyrousa, Phacochoerus (wart hogs), and Sus, the latter containing the domestic pig (see SUS SCROFA).

A dead body, usually a human body.

The administration of substances into the VITREOUS BODY of the eye with a hypodermic syringe.

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.

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.

Stratified squamous epithelium that covers the outer surface of the CORNEA. It is smooth and contains many free nerve endings.

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.

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.

Method of making images on a sensitized surface by exposure to light or other radiant energy.

Single layer of large flattened cells covering the surface of the cornea.

General increase in bulk of a part or organ due to CELL ENLARGEMENT and accumulation of FLUIDS AND SECRETIONS, not due to tumor formation, nor to an increase in the number of cells (HYPERPLASIA).

Maleness or femaleness as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or effect of a circumstance. It is used with human or animal concepts but should be differentiated from SEX CHARACTERISTICS, anatomical or physiological manifestations of sex, and from SEX DISTRIBUTION, the number of males and females in given circumstances.

Persistently high systemic arterial BLOOD PRESSURE. Based on multiple readings (BLOOD PRESSURE DETERMINATION), hypertension is currently defined as when SYSTOLIC PRESSURE is consistently greater than 140 mm Hg or when DIASTOLIC PRESSURE is consistently 90 mm Hg or more.

A synovial hinge connection formed between the bones of the FEMUR; TIBIA; and PATELLA.

Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.

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)

Methods developed to aid in the interpretation of ultrasound, radiographic images, etc., for diagnosis of disease.

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)

Bleeding from blood vessels in the UTERUS, sometimes manifested as vaginal bleeding.

An indicator of body density as determined by the relationship of BODY WEIGHT to BODY HEIGHT. BMI=weight (kg)/height squared (m2). BMI correlates with body fat (ADIPOSE TISSUE). Their relationship varies with age and gender. For adults, BMI falls into these categories: below 18.5 (underweight); 18.5-24.9 (normal); 25.0-29.9 (overweight); 30.0 and above (obese). (National Center for Health Statistics, Centers for Disease Control and Prevention)

The use of green light-producing LASERS to stop bleeding. The green light is selectively absorbed by HEMOGLOBIN, thus triggering BLOOD COAGULATION.

Surgical procedures employed to correct REFRACTIVE ERRORS such as MYOPIA; HYPEROPIA; or ASTIGMATISM. These may involve altering the curvature of the CORNEA; removal or replacement of the CRYSTALLINE LENS; or modification of the SCLERA to change the axial length of the eye.

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.

Deviations from the average or standard indices of refraction of the eye through its dioptric or refractive apparatus.

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.

A computer based method of simulating or analyzing the behavior of structures or components.

The veins and arteries of the HEART.

Measurable and quantifiable biological parameters (e.g., specific enzyme concentration, specific hormone concentration, specific gene phenotype distribution in a population, presence of biological substances) which serve as indices for health- and physiology-related assessments, such as disease risk, psychiatric disorders, environmental exposure and its effects, disease diagnosis, metabolic processes, substance abuse, pregnancy, cell line development, epidemiologic studies, etc.

Studies in which subsets of a defined population are identified. These groups may or may not be exposed to factors hypothesized to influence the probability of the occurrence of a particular disease or other outcome. Cohorts are defined populations which, as a whole, are followed in an attempt to determine distinguishing subgroup characteristics.

A specialized CONNECTIVE TISSUE that is the main constituent of the SKELETON. The principle cellular component of bone is comprised of OSTEOBLASTS; OSTEOCYTES; and OSTEOCLASTS, while FIBRILLAR COLLAGENS and hydroxyapatite crystals form the BONE MATRIX.

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.

A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.

A process involving chance used in therapeutic trials or other research endeavor for allocating experimental subjects, human or animal, between treatment and control groups, or among treatment groups. It may also apply to experiments on inanimate objects.

Methods of creating machines and devices.

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).

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.

The number of CELLS of a specific kind, usually measured per unit volume or area of sample.

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)

The beginning third of a human PREGNANCY, from the first day of the last normal menstrual period (MENSTRUATION) through the completion of 14 weeks (98 days) of gestation.

Tongues of skin and subcutaneous tissue, sometimes including muscle, cut away from the underlying parts but often still attached at one end. They retain their own microvasculature which is also transferred to the new site. They are often used in plastic surgery for filling a defect in a neighboring region.

The amount of mineral per square centimeter of BONE. This is the definition used in clinical practice. Actual bone density would be expressed in grams per milliliter. It is most frequently measured by X-RAY ABSORPTIOMETRY or TOMOGRAPHY, X RAY COMPUTED. Bone density is an important predictor for OSTEOPOROSIS.

Levels within a diagnostic group which are established by various measurement criteria applied to the seriousness of a patient's disorder.

Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.

A darkly stained mat-like EXTRACELLULAR MATRIX (ECM) that separates cell layers, such as EPITHELIUM from ENDOTHELIUM or a layer of CONNECTIVE TISSUE. The ECM layer that supports an overlying EPITHELIUM or ENDOTHELIUM is called basal lamina. Basement membrane (BM) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. BM, composed mainly of TYPE IV COLLAGEN; glycoprotein LAMININ; and PROTEOGLYCAN, provides barriers as well as channels between interacting cell layers.

Muscles forming the ABDOMINAL WALL including RECTUS ABDOMINIS, external and internal oblique muscles, transversus abdominis, and quadratus abdominis. (from Stedman, 25th ed)

Tissue that supports and binds other tissues. It consists of CONNECTIVE TISSUE CELLS embedded in a large amount of EXTRACELLULAR MATRIX.

A transparent, biconvex structure of the EYE, enclosed in a capsule and situated behind the IRIS and in front of the vitreous humor (VITREOUS BODY). It is slightly overlapped at its margin by the ciliary processes. Adaptation by the CILIARY BODY is crucial for OCULAR ACCOMMODATION.

X-RAY COMPUTERIZED TOMOGRAPHY with resolution in the micrometer range.

The visualization of tissues during pregnancy through recording of the echoes of ultrasonic waves directed into the body. The procedure may be applied with reference to the mother or the fetus and with reference to organs or the detection of maternal or fetal disease.

In utero measurement corresponding to the sitting height (crown to rump) of the fetus. Length is considered a more accurate criterion of the age of the fetus than is the weight. The average crown-rump length of the fetus at term is 36 cm. (From Williams Obstetrics, 18th ed, p91)

The mechanical property of material that determines its resistance to force. HARDNESS TESTS measure this property.

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.

The fluid secreted by the lacrimal glands. This fluid moistens the CONJUNCTIVA and CORNEA.

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)

The main artery of the thigh, a continuation of the external iliac artery.

Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.

Recording of electric potentials in the retina after stimulation by light.

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 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.

Artificially produced membranes, such as semipermeable membranes used in artificial kidney dialysis (RENAL DIALYSIS), monomolecular and bimolecular membranes used as models to simulate biological CELL MEMBRANES. These membranes are also used in the process of GUIDED TISSUE REGENERATION.

A conical fibro-serous sac surrounding the HEART and the roots of the great vessels (AORTA; VENAE CAVAE; PULMONARY ARTERY). Pericardium consists of two sacs: the outer fibrous pericardium and the inner serous pericardium. The latter consists of an outer parietal layer facing the fibrous pericardium, and an inner visceral layer (epicardium) resting next to the heart, and a pericardial cavity between these two layers.

Lesions formed within the walls of ARTERIES.

Lenses designed to be worn on the front surface of the eyeball. (UMDNS, 1999)

An increase in the number of cells in a tissue or organ without tumor formation. It differs from HYPERTROPHY, which is an increase in bulk without an increase in the number of cells.

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.

Diseases of the cornea.

Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.

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 geometric and structural changes that the HEART VENTRICLES undergo, usually following MYOCARDIAL INFARCTION. It comprises expansion of the infarct and dilatation of the healthy ventricle segments. While most prevalent in the left ventricle, it can also occur in the right ventricle.

A light microscopic technique in which only a small spot is illuminated and observed at a time. An image is constructed through point-by-point scanning of the field in this manner. Light sources may be conventional or laser, and fluorescence or transmitted observations are possible.

The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.

The physical state of supporting an applied load. This often refers to the weight-bearing bones or joints that support the body's weight, especially those in the spine, hip, knee, and foot.

The hemodynamic and electrophysiological action of the left HEART VENTRICLE. Its measurement is an important aspect of the clinical evaluation of patients with heart disease to determine the effects of the disease on cardiac performance.

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.

Three-dimensional representation to show anatomic structures. Models may be used in place of intact animals or organisms for teaching, practice, and study.

Pathological conditions involving the CARDIOVASCULAR SYSTEM including the HEART; the BLOOD VESSELS; or the PERICARDIUM.

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)

Those characteristics that distinguish one SEX from the other. The primary sex characteristics are the OVARIES and TESTES and their related hormones. Secondary sex characteristics are those which are masculine or feminine but not directly related to reproduction.

A generic term for fats and lipoids, the alcohol-ether-soluble constituents of protoplasm, which are insoluble in water. They comprise the fats, fatty oils, essential oils, waxes, phospholipids, glycolipids, sulfolipids, aminolipids, chromolipids (lipochromes), and fatty acids. (Grant & Hackh's Chemical Dictionary, 5th ed)

Narrowing or stricture of any part of the CAROTID ARTERIES, most often due to atherosclerotic plaque formation. Ulcerations may form in atherosclerotic plaques and induce THROMBUS formation. Platelet or cholesterol emboli may arise from stenotic carotid lesions and induce a TRANSIENT ISCHEMIC ATTACK; CEREBROVASCULAR ACCIDENT; or temporary blindness (AMAUROSIS FUGAX). (From Adams et al., Principles of Neurology, 6th ed, pp 822-3)

A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

A set of techniques used when variation in several variables has to be studied simultaneously. In statistics, multivariate analysis is interpreted as any analytic method that allows simultaneous study of two or more dependent variables.

That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.

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)

A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of SKIN; CONNECTIVE TISSUE; and the organic substance of bones (BONE AND BONES) and teeth (TOOTH).

Computer systems or networks designed to provide radiographic interpretive information.

Restoration of integrity to traumatized tissue.

The aorta from the DIAPHRAGM to the bifurcation into the right and left common iliac arteries.

Pathological processes of CORONARY ARTERIES that may derive from a congenital abnormality, atherosclerotic, or non-atherosclerotic cause.

Post-systolic relaxation of the HEART, especially the HEART VENTRICLES.

Either one of the two small elongated rectangular bones that together form the bridge of the nose.

The qualitative or quantitative estimation of the likelihood of adverse effects that may result from exposure to specified health hazards or from the absence of beneficial influences. (Last, Dictionary of Epidemiology, 1988)

The science and art of collecting, summarizing, and analyzing data that are subject to random variation. The term is also applied to the data themselves and to the summarization of the data.

The continuation of the axillary artery; it branches into the radial and ulnar arteries.

A class of statistical methods applicable to a large set of probability distributions used to test for correlation, location, independence, etc. In most nonparametric statistical tests, the original scores or observations are replaced by another variable containing less information. An important class of nonparametric tests employs the ordinal properties of the data. Another class of tests uses information about whether an observation is above or below some fixed value such as the median, and a third class is based on the frequency of the occurrence of runs in the data. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed, p1284; Corsini, Concise Encyclopedia of Psychology, 1987, p764-5)

A type of porcelain used in dental restorations, either jacket crowns or inlays, artificial teeth, or metal-ceramic crowns. It is essentially a mixture of particles of feldspar and quartz, the feldspar melting first and providing a glass matrix for the quartz. Dental porcelain is produced by mixing ceramic powder (a mixture of quartz, kaolin, pigments, opacifiers, a suitable flux, and other substances) with distilled water. (From Jablonski's Dictionary of Dentistry, 1992)

Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes.

The carbohydrate-rich zone on the cell surface. This zone can be visualized by a variety of stains as well as by its affinity for lectins. Although most of the carbohydrate is attached to intrinsic plasma membrane molecules, the glycocalyx usually also contains both glycoproteins and proteoglycans that have been secreted into the extracellular space and then adsorbed onto the cell surface. (Alberts et al., Molecular Biology of the Cell, 3d ed, p502)

Studies in which variables relating to an individual or group of individuals are assessed over a period of time.

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)

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.

The maximum stress a material subjected to a stretching load can withstand without tearing. (McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed, p2001)