Vision Disparity: The difference between two images on the retina when looking at a visual stimulus. This occurs since the two retinas do not have the same view of the stimulus because of the location of our eyes. Thus the left eye does not get exactly the same view as the right eye.Healthcare Disparities: Differences in access to or availability of medical facilities and services.Health Status Disparities: Variation in rates of disease occurrence and disabilities between population groups defined by socioeconomic characteristics such as age, ethnicity, economic resources, or gender and populations identified geographically or similar measures.Vision, Ocular: The process in which light signals are transformed by the PHOTORECEPTOR CELLS into electrical signals which can then be transmitted to the brain.Vision, Low: 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.).Vision Disorders: 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).Vision, Binocular: The blending of separate images seen by each eye into one composite image.Vision Tests: A series of tests used to assess various functions of the eyes.Depth Perception: Perception of three-dimensionality.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.Vision, Monocular: Images seen by one eye.European Continental Ancestry Group: Individuals whose ancestral origins are in the continent of Europe.United StatesAfrican Americans: Persons living in the United States having origins in any of the black groups of Africa.Visual Acuity: 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.Ethnic Groups: A group of people with a common cultural heritage that sets them apart from others in a variety of social relationships.Continental Population Groups: Groups of individuals whose putative ancestry is from native continental populations based on similarities in physical appearance.Night Vision: Function of the human eye that is used in dim illumination (scotopic intensities) or at nighttime. Scotopic vision is performed by RETINAL ROD PHOTORECEPTORS with high sensitivity to light and peak absorption wavelength at 507 nm near the blue end of the spectrum.Convergence, Ocular: The turning inward of the lines of sight toward each other.Photic Stimulation: Investigative technique commonly used during ELECTROENCEPHALOGRAPHY in which a series of bright light flashes or visual patterns are used to elicit brain activity.Hispanic Americans: Persons living in the United States of Mexican (MEXICAN AMERICANS), Puerto Rican, Cuban, Central or South American, or other Spanish culture or origin. The concept does not include Brazilian Americans or Portuguese Americans.Psychophysics: The science dealing with the correlation of the physical characteristics of a stimulus, e.g., frequency or intensity, with the response to the stimulus, in order to assess the psychologic factors involved in the relationship.Health Services Accessibility: The degree to which individuals are inhibited or facilitated in their ability to gain entry to and to receive care and services from the health care system. Factors influencing this ability include geographic, architectural, transportational, and financial considerations, among others.Socioeconomic Factors: Social and economic factors that characterize the individual or group within the social structure.Minority Groups: A subgroup having special characteristics within a larger group, often bound together by special ties which distinguish it from the larger group.Contrast Sensitivity: 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.Blindness: 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.Social Justice: An interactive process whereby members of a community are concerned for the equality and rights of all.Color Perception: Mental processing of chromatic signals (COLOR VISION) from the eye by the VISUAL CORTEX where they are converted into symbolic representations. Color perception involves numerous neurons, and is influenced not only by the distribution of wavelengths from the viewed object, but also by its background color and brightness contrast at its boundary.Color Perception Tests: Type of vision test used to determine COLOR VISION DEFECTS.Visual Fields: The total area or space visible in a person's peripheral vision with the eye looking straightforward.Sensory Thresholds: The minimum amount of stimulus energy necessary to elicit a sensory response.African Continental Ancestry Group: Individuals whose ancestral origins are in the continent of Africa.Visual Perception: The selecting and organizing of visual stimuli based on the individual's past experience.Visually Impaired Persons: Persons with loss of vision such that there is an impact on activities of daily living.Visual Cortex: Area of the OCCIPITAL LOBE concerned with the processing of visual information relayed via VISUAL PATHWAYS.Pattern Recognition, Visual: Mental process to visually perceive a critical number of facts (the pattern), such as characters, shapes, displays, or designs.Prejudice: A preconceived judgment made without factual basis.Motion Perception: The real or apparent movement of objects through the visual field.Eyeglasses: A pair of ophthalmic lenses in a frame or mounting which is supported by the nose and ears. The purpose is to aid or improve vision. It does not include goggles or nonprescription sun glasses for which EYE PROTECTIVE DEVICES is available.Form Perception: The sensory discrimination of a pattern shape or outline.Social Class: A stratum of people with similar position and prestige; includes social stratification. Social class is measured by criteria such as education, occupation, and income.Orientation: Awareness of oneself in relation to time, place and person.Eye Movements: Voluntary or reflex-controlled movements of the eye.Fixation, Ocular: The positioning and accommodation of eyes that allows the image to be brought into place on the FOVEA CENTRALIS of each eye.Lighting: The illumination of an environment and the arrangement of lights to achieve an effect or optimal visibility. Its application is in domestic or in public settings and in medical and non-medical environments.Amblyopia: 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.Poverty: A situation in which the level of living of an individual, family, or group is below the standard of the community. It is often related to a specific income level.Sensory Aids: Devices that help people with impaired sensory responses.Visual Pathways: 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.Strabismus: 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)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.Refractive Errors: Deviations from the average or standard indices of refraction of the eye through its dioptric or refractive apparatus.Size Perception: The sensory interpretation of the dimensions of objects.Asian Americans: Persons living in the United States having origins in any of the original peoples of the Far East, Southeast Asia, or the Indian subcontinent.Healthy People Programs: Healthy People Programs are a set of health objectives to be used by governments, communities, professional organizations, and others to help develop programs to improve health. It builds on initiatives pursued over the past two decades beginning with the 1979 Surgeon General's Report, Healthy People, Healthy People 2000: National Health Promotion and Disease Prevention Objectives, and Healthy People 2010. These established national health objectives and served as the basis for the development of state and community plans. These are administered by the Office of Disease Prevention and Health Promotion (ODPHP). Similar programs are conducted by other national governments.Cultural Diversity: Coexistence of numerous distinct ethnic, racial, religious, or cultural groups within one social unit, organization, or population. (From American Heritage Dictionary, 2d college ed., 1982, p955)Discrimination (Psychology): Differential response to different stimuli.Distance Perception: The act of knowing or the recognition of a distance by recollective thought, or by means of a sensory process which is under the influence of set and of prior experience.Cues: Signals for an action; that specific portion of a perceptual field or pattern of stimuli to which a subject has learned to respond.Space Perception: The awareness of the spatial properties of objects; includes physical space.Institute of Medicine (U.S.): Identifies, for study and analysis, important issues and problems that relate to health and medicine. The Institute initiates and conducts studies of national policy and planning for health care and health-related education and research; it also responds to requests from the federal government and other agencies for studies and advice.Fovea Centralis: 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)Retina: 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.Mesopic Vision: The function of the eye that is used in the intermediate level of illumination (mesopic intensities) where both the RETINAL ROD PHOTORECEPTORS and the RETINAL CONE PHOTORECEPTORS are active in processing light input simultaneously.Optical Illusions: An illusion of vision usually affecting spatial relations.Adaptation, Ocular: The adjustment of the eye to variations in the intensity of light. Light adaptation is the adjustment of the eye when the light threshold is increased; DARK ADAPTATION when the light is greatly reduced. (From Cline et al., Dictionary of Visual Science, 4th ed)Eye Diseases: Diseases affecting the eye.Opsins: Photosensitive proteins in the membranes of PHOTORECEPTOR CELLS such as the rods and the cones. Opsins have varied light absorption properties and are members of the G-PROTEIN-COUPLED RECEPTORS family. Their ligands are VITAMIN A-based chromophores.Risk Factors: 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.Quality of Health Care: The levels of excellence which characterize the health service or health care provided based on accepted standards of quality.Income: Revenues or receipts accruing from business enterprise, labor, or invested capital.Models, Neurological: Theoretical representations that simulate the behavior or activity of the neurological system, processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.Afterimage: Continuation of visual impression after cessation of stimuli causing the original image.Sex Factors: 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.Logistic Models: Statistical models which describe the relationship between a qualitative dependent variable (that is, one which can take only certain discrete values, such as the presence or absence of a disease) and an independent variable. A common application is in epidemiology for estimating an individual's risk (probability of a disease) as a function of a given risk factor.Cross-Sectional Studies: 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.Residence Characteristics: Elements of residence that characterize a population. They are applicable in determining need for and utilization of health services.Cultural Competency: Cultural and linguistic competence is a set of congruent behaviors, attitudes, and policies that come together in a system, agency, or among professionals that enables effective work in cross-cultural situations. Competence implies the capacity to function effectively as an individual and an organization within the context of the cultural beliefs, behaviors, and needs presented by consumers and their communities.Educational Status: Educational attainment or level of education of individuals.Ophthalmology: A surgical specialty concerned with the structure and function of the eye and the medical and surgical treatment of its defects and diseases.Macular Degeneration: 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.Prevalence: The total number of cases of a given disease in a specified population at a designated time. It is differentiated from INCIDENCE, which refers to the number of new cases in the population at a given time.Delivery of Health Care: The concept concerned with all aspects of providing and distributing health services to a patient population.Racism: Differential treatment or unequal access to opportunities, based on group membership such as origin or ethnicity.Community-Institutional Relations: The interactions between members of a community and representatives of the institutions within that community.Oceanic Ancestry Group: Individuals whose ancestral origins are in the islands of the central and South Pacific, including Micronesia, Melanesia, Polynesia, and traditionally Australasia.Retinal Pigments: 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.FloridaIndians, North American: Individual members of North American ethnic groups with ancient historic ancestral origins in Asia.Vulnerable Populations: Groups of persons whose range of options is severely limited, who are frequently subjected to COERCION in their DECISION MAKING, or who may be compromised in their ability to give INFORMED CONSENT.Community-Based Participatory Research: Collaborative process of research involving researchers and community representatives.Health Care Surveys: Statistical measures of utilization and other aspects of the provision of health care services including hospitalization and ambulatory care.Sociology, Medical: The study of the social determinants and social effects of health and disease, and of the social structure of medical institutions or professions.Time Factors: Elements of limited time intervals, contributing to particular results or situations.SEER Program: A cancer registry mandated under the National Cancer Act of 1971 to operate and maintain a population-based cancer reporting system, reporting periodically estimates of cancer incidence and mortality in the United States. The Surveillance, Epidemiology, and End Results (SEER) Program is a continuing project of the National Cancer Institute of the National Institutes of Health. Among its goals, in addition to assembling and reporting cancer statistics, are the monitoring of annual cancer incident trends and the promoting of studies designed to identify factors amenable to cancer control interventions. (From National Cancer Institute, NIH Publication No. 91-3074, October 1990)Health Surveys: A systematic collection of factual data pertaining to health and disease in a human population within a given geographic area.Cataract: Partial or complete opacity on or in the lens or capsule of one or both eyes, impairing vision or causing blindness. The many kinds of cataract are classified by their morphology (size, shape, location) or etiology (cause and time of occurrence). (Dorland, 27th ed)Retrospective Studies: 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.CaliforniaAge Factors: 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.Sensory Deprivation: The absence or restriction of the usual external sensory stimuli to which the individual responds.Health Services Research: The integration of epidemiologic, sociological, economic, and other analytic sciences in the study of health services. Health services research is usually concerned with relationships between need, demand, supply, use, and outcome of health services. The aim of the research is evaluation, particularly in terms of structure, process, output, and outcome. (From Last, Dictionary of Epidemiology, 2d ed)Southeastern United States: The geographic area of the southeastern region of the United States in general or when the specific state or states are not included. The states usually included in this region are Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, West Virginia, and Virginia.Accommodation, Ocular: 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)Insurance, Health: Insurance providing coverage of medical, surgical, or hospital care in general or for which there is no specific heading.Models, Psychological: Theoretical representations that simulate psychological processes and/or social processes. These include the use of mathematical equations, computers, and other electronic equipment.ReadingElectroretinography: Recording of electric potentials in the retina after stimulation by light.Rod Opsins: Photosensitive proteins expressed in the ROD PHOTORECEPTOR CELLS. They are the protein components of rod photoreceptor pigments such as RHODOPSIN.Scotoma: 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.Health Policy: Decisions, usually developed by government policymakers, for determining present and future objectives pertaining to the health care system.Macaca mulatta: A species of the genus MACACA inhabiting India, China, and other parts of Asia. The species is used extensively in biomedical research and adapts very well to living with humans.Presbyopia: The normal decreasing elasticity of the crystalline lens that leads to loss of accommodation.Urban Population: The inhabitants of a city or town, including metropolitan areas and suburban areas.Neural Analyzers: A term used in Eastern European research literature for the functional neural unit that provides the basis for differential sensitivity; the analyzer consists of receptor, afferent nerves, and their central connections. (From Campbell's Psychiatric Dictionary, 8th ed.)Emigrants and Immigrants: People who leave their place of residence in one country and settle in a different country.Insurance Coverage: Generally refers to the amount of protection available and the kind of loss which would be paid for under an insurance contract with an insurer. (Slee & Slee, Health Care Terms, 2d ed)Health Status: The level of health of the individual, group, or population as subjectively assessed by the individual or by more objective measures.Health Status Indicators: The measurement of the health status for a given population using a variety of indices, including morbidity, mortality, and available health resources.Questionnaires: Predetermined sets of questions used to collect data - clinical data, social status, occupational group, etc. The term is often applied to a self-completed survey instrument.Ocular Physiological Phenomena: Processes and properties of the EYE as a whole or of any of its parts.Health Services Needs and Demand: Health services required by a population or community as well as the health services that the population or community is able and willing to pay for.Light: That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.Community Networks: Organizations and individuals cooperating together toward a common goal at the local or grassroots level.Vision, Entoptic: Visual sensation derived from sensory stimulation by objects or shadows inside the eye itself, such as floating vitreous fibers, tissues, or blood.Perceptual Masking: The interference of one perceptual stimulus with another causing a decrease or lessening in perceptual effectiveness.South CarolinaRace Relations: Cultural contacts between people of different races.Infant, Newborn: An infant during the first month after birth.Evoked Potentials, Visual: The electric response evoked in the cerebral cortex by visual stimulation or stimulation of the visual pathways.Glare: 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)Medicare: Federal program, created by Public Law 89-97, Title XVIII-Health Insurance for the Aged, a 1965 amendment to the Social Security Act, that provides health insurance benefits to persons over the age of 65 and others eligible for Social Security benefits. It consists of two separate but coordinated programs: hospital insurance (MEDICARE PART A) and supplementary medical insurance (MEDICARE PART B). (Hospital Administration Terminology, AHA, 2d ed and A Discursive Dictionary of Health Care, US House of Representatives, 1976)Incidence: The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from PREVALENCE, which refers to all cases, new or old, in the population at a given time.Censuses: Enumerations of populations usually recording identities of all persons in every place of residence with age or date of birth, sex, occupation, national origin, language, marital status, income, relation to head of household, information on the dwelling place, education, literacy, health-related data (e.g., permanent disability), etc. The census or "numbering of the people" is mentioned several times in the Old Testament. Among the Romans, censuses were intimately connected with the enumeration of troops before and after battle and probably a military necessity. (From Last, A Dictionary of Epidemiology, 3d ed; Garrison, An Introduction to the History of Medicine, 4th ed, p66, p119)Dominance, Ocular: 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.Normal Distribution: Continuous frequency distribution of infinite range. Its properties are as follows: 1, continuous, symmetrical distribution with both tails extending to infinity; 2, arithmetic mean, mode, and median identical; and 3, shape completely determined by the mean and standard deviation.Alaska
Low vision assessment: Low vision is both a subspeciality and a condition. Optometrists and Ophthalmologists after their training may undergo further training in Low vision assessment and management.Operation Eyesight Universal: Operation Eyesight Universal is a Canada-based international development organisation, founded in 1963. It works to prevent avoidable blindness and to cure blindness that is treatable.Binocular vision: Binocular vision is vision in which creatures having two eyes use them together. The word binocular comes from two Latin roots, bini for double, and oculus for eye.Landolt CStereopsis: Stereopsis (from the Greek στερεο- [meaning "solid", and ὄψις] opsis, "appearance, [[visual perception|sight") is a term that is most often used to refer to the perception of depth and 3-dimensional structure obtained on the basis of visual information deriving from two eyes by individuals with normally developed binocular vision.Gene therapy for color blindness: Gene therapy for color blindness is an experimental gene therapy aiming to convert congenitally colorblind individuals to trichromats by introducing a photopigment gene that they lack. Though partial color blindness is considered only a mild disability and is controversial whether it is even a disorder, it is a condition that affects many people, particularly males.List of Parliamentary constituencies in Kent: The ceremonial county of Kent,African-American family structure: The family structure of African-Americans has long been a matter of national public policy interest.Moynihan's War on Poverty report A 1965 report by Daniel Patrick Moynihan, known as The Moynihan Report, examined the link between black poverty and family structure.LogMAR chart: A LogMAR chart comprises rows of letters and is used by ophthalmologists and vision scientists to estimate visual acuity. This chart was developed at the National Vision Research Institute of Australia in 1976, and is designed to enable a more accurate estimate of acuity as compared to other charts (e.Tactical light: A tactical light is a flashlight used in conjunction with a firearm to aid low light target identification, allowing the marksman to simultaneously aim and illuminate the target. Tactical lights can be handheld or mounted to the weapon with the light beam parallel to the bore.Convergence of measures: In mathematics, more specifically measure theory, there are various notions of the convergence of measures. For an intuitive general sense of what is meant by convergence in measure, consider a sequence of measures μn on a space, sharing a common collection of measurable sets.Korte's law: In psychophysics, Korte's law, also known more completely as Korte's third law of apparent motion, is an observation relating the phenomenon of apparent motion to the distance and duration between two successively presented stimuli. It was originally proposed in 1915 by Adolf Korte.Ethnic groups in the United Kingdom: People from various ethnic groups reside in the United Kingdom. Migration from Northern Europe has been happening for millennia, with other groups such as British Jews also well established.Blind People's Association: The Blind People’s Association (BPA) is an organisation in India which promotes comprehensive rehabilitation of persons with all categories of disabilities through education, training, employment, community based rehabilitation, integrated education, research, publications, human resource development and other innovative means.Injustice SocietyFarnsworth Lantern Test: The Farnsworth Lantern Test, or FALANT, is a test of color vision originally developed specifically to screen sailors for shipboard tasks requiring color vision, such as identifying signal lights at night. It screens for red-green deficiencies, but not the much rarer blue color deficiency.Meridian (perimetry, visual field): Meridian (plural: "meridians") is used in perimetry and in specifying visual fields. According to IPS Perimetry Standards 1978 (2002): "Perimetry is the measurement of [an observer's] visual functions ...Percolation threshold: Percolation threshold is a mathematical concept related to percolation theory, which is the formation of long-range connectivity in random systems. Below the threshold a giant connected component does not exist; while above it, there exists a giant component of the order of system size.Pride and Prejudice and Zombies: Dawn of the Dreadfuls: Pride and Prejudice and Zombies: Dawn of the Dreadfuls (2010) is a parody novel by Steve Hockensmith. It is a prequel to Seth Grahame-Smith's 2009 novel Pride and Prejudice and Zombies, focusing on "the early life and training of Elizabeth Bennet, heroine of the earlier Pride and Prejudice and Zombies as she strove to become a gifted zombie hunter, with some mishaps in her early romantic encounters also included.Biological motion: Biological motion is a term used by social and cognitive neuroscientists to refer to the unique visual phenomenon of a moving, animate object. Often, the stimuli used in biological motion experiments are just a few moving dots that reflect the motion of some key joints of the moving organism.Rimless eyeglasses: Rimless eyeglasses, are a type of eyeglasses in which the lenses are mounted directly to the bridge and/or temples. The style is divided into two subtypes: three piece glasses are composed of lenses mounted to a bridge and two separate temple arms, while rimways (also called cortlands) feature a supporting arch that connects the temples to the bridge and provides extra stability for the lenses.Relative index of inequality: The relative index of inequality (RII) is a regression-based index which summarizes the magnitude of socio-economic status (SES) as a source of inequalities in health. RII is useful because it takes into account the size of the population and the relative disadvantage experienced by different groups.Canon EOS 5Plastic headlight restorationAmblyopiaPoverty trap: A poverty trap is "any self-reinforcing mechanism which causes poverty to persist."Costas Azariadis and John Stachurski, "Poverty Traps," Handbook of Economic Growth, 2005, 326.Braille technology: Braille technology is assistive technology which allows blind or visually impaired people to do common tasks such as writing, browsing the Internet, typing in Braille and printing in text, engaging in chat, downloading files, music, using electronic mail, burning music, and reading documents. It also allows blind or visually impaired students to complete all assignments in school as the rest of sighted classmates and allows them take courses online.StrabismusAutorefractor: An autorefractor or automated refractor is a computer-controlled machine used during an eye examination to provide an objective measurement of a person's refractive error and prescription for glasses or contact lenses. This is achieved by measuring how light is changed as it enters a person's eye.Subatomic scale: The subatomic scale is the domain of physical size that encompasses objects smaller than an atom. It is the scale at which the atomic constituents, such as the nucleus containing protons and neutrons, and the electrons, which orbit in spherical or elliptical paths around the nucleus, become apparent.Healthy People program: Healthy People is a program of nationwide health-promotion and disease-prevention goals set by the United States Department of Health and Human Services. The goals were first set in 1979 “in response to an emerging consensus among scientists and health authorities that national health priorities should emphasize disease prevention”.Perspective distortion (photography): Perspective correction}}Cue stick: A cue stick (or simply cue, more specifically pool cue, snooker cue, or billiards cue), is an item of sporting equipment essential to the games of pool, snooker and carom billiards. It is used to strike a ball, usually the .Macula of retina: The macula or macula lutea (from Latin macula, "spot" + lutea, "yellow") is an oval-shaped pigmented area near the center of the retina of the human eye. It has a diameter of around .Retinal regeneration: Retinal regeneration deals with restoring retinal function to vertebrates so impaired.Photopic vision: Photopic vision is the vision of the eye under well-lit conditions. In humans and many other animals, photopic vision allows color perception, mediated by cone cells, and a significantly higher visual acuity and temporal resolution than available with scotopic vision.List of optical illusions: This is a list of optical illusions.Neuro-ophthalmology: Neuro-ophthalmology is an academically-oriented subspecialty that merges the fields of neurology and ophthalmology, often dealing with complex systemic diseases that have manifestations in the visual system. Neuro-ophthalmologists initially complete a residency in either neurology or ophthalmology, then do a fellowship in the complementary field.OpsinQRISK: QRISK2 (the most recent version of QRISK) is a prediction algorithm for cardiovascular disease (CVD) that uses traditional risk factors (age, systolic blood pressure, smoking status and ratio of total serum cholesterol to high-density lipoprotein cholesterol) together with body mass index, ethnicity, measures of deprivation, family history, chronic kidney disease, rheumatoid arthritis, atrial fibrillation, diabetes mellitus, and antihypertensive treatment.Circular flow of income: The circular flow of income or circular flow is a model of the economy in which the major exchanges are represented as flows of money, goods and services, etc. between economic agents.Neighbourhood: A neighbourhood (Commonwealth English), or neighborhood (American English), is a geographically localised community within a larger city, town, suburb or rural area. Neighbourhoods are often social communities with considerable face-to-face interaction among members.Business Model of Intercultural Analysis: The Business Model of Intercultural Analysis (BMIA) is a tool developed to address cross-cultural problems. The BMIA framework uses six comprehension lenses to analyze cross-cultural interaction in the business environment.Pediatric ophthalmology: Pediatric ophthalmology is a sub-speciality of ophthalmology concerned with eye diseases, visual development, and vision care in children.Age-Related Eye Disease Study: The Age-Related Eye Disease Study (AREDS) was a clinical trial sponsored by the National Eye Institute, one of the National Institutes of Health in the United States.A Randomized, Placebo-Controlled, Clinical Trial of High-Dose Supplementation With Vitamins C and E, Beta Carotene, and Zinc for Age-Related Macular Degeneration and Vision Loss.Global Health Delivery ProjectHaridas ChaudhuriVibe Australia: Vibe Australia Pty Ltd (Vibe) is an Aboriginal media, communications and events management agency. Located in Darlinghurst, Sydney, New South Wales, they work with Aboriginal and Torres Strait Islander people throughout Australia.Photopigment: Photopigments are unstable pigments that undergo a chemical change when they absorb light. The term is generally applied to the non-protein chromophore moiety of photosensitive chromoproteins, such as the pigments involved in photosynthesis and photoreception.Miami-Dade County Corrections and Rehabilitation Department: The Miami-Dade County Corrections and Rehabilitation Department is an agency of the government of Miami-Dade County, Florida. It has its headquarters in the Gladeview census-designated place in an unincorporated area.Robinson Rancheria of Pomo Indians of California: The Robinson Rancheria of Pomo Indians of California is a federally recognized tribe of Eastern Pomo people in Lake County, California.California Indians and Their Reservations.History of sociology: Sociology as a scholarly discipline emerged primarily out of enlightenment thought, shortly after the French Revolution, as a positivist science of society. Its genesis owed to various key movements in the philosophy of science and the philosophy of knowledge.Temporal analysis of products: Temporal Analysis of Products (TAP), (TAP-2), (TAP-3) is an experimental technique for studyingCongenital cataractSan Diego County, California Probation: The San Diego County Probation Department is the body in San Diego County, California responsible for supervising convicted offenders in the community, either who are on probation, such as at the conclusion of their sentences, or while on community supervision orders.
(1/810) Temporal aspects of stereoscopic slant estimation: an evaluation and extension of Howard and Kaneko's theory.
We investigated temporal aspects of stereoscopically perceived slant produced by the following transformations: horizontal scale, horizontal shear, vertical scale, vertical shear, divergence and rotation, between the half-images of a stereogram. Six subjects viewed large field stimuli (70 degrees diameter) both in the presence and in the absence of a visual reference. The presentation duration was: 0.1, 0.4, 1.6, 6.4 or 25.6 s. Without reference we found the following: rotation and divergence evoked considerable perceived slant in a number of subjects. This finding violates the recently published results of Howard and Kaneko. Slant evoked by vertical scale and shear was similar to slant evoked by horizontal scale and shear but was generally less. With reference we found the following: vertical scale and vertical shear did not evoke slant. Slant due to rotation and divergence was similar to slant due to horizontal scale and shear but was generally less. According to the theory of Howard and Kaneko, perceived slant depends on the difference between horizontal and vertical scale and shear disparities. We made their theory more explicit by translating their proposals into linear mathematical expressions that contain weighting factors that allow for both slant evoked by rotation or divergence, subject-dependent underestimation of slant and other related phenomena reported in the literature. Our data for all stimulus durations and for all subjects is explained by this 'unequal-weighting' extension of Howard and Kaneko's theory. (+info)
(2/810) Monocular occlusion cues alter the influence of terminator motion in the barber pole phenomenon.
The influence of monocular occlusion cues on the perceived direction of motion of barber pole patterns is examined. Unlike previous studies that have emphasized the importance of binocular disparity, we find that monocular cues strongly influence the perceived motion direction and can even override binocular depth cues. The difference in motion bias for occluders with and without disparity cues is relatively small. Additionally, although 'T-junctions' aligned with occluders are particularly important, they are not strictly necessary for creating a change in motion perception. Finally, the amount of motion bias differs for several stimulus configurations, suggesting that the extrinsic/intrinsic classification of terminators is not all-or-none. (+info)
(3/810) The effects of contrast on perceived depth and depth discrimination.
The contrast dependence of perceived depth was quantified through a series of depth matching experiments. Perceived depth was found to be a power law function of contrast. In addition, subjects exhibited a large uncrossed depth bias indicating that low contrast test patterns appeared much farther away than high contrast patterns of equal disparity. For disparities in the range of +/- 4.0 arc min, matching disparities for low contrast patterns were shifted in the uncrossed direction by the same amount. In other words, while the magnitude of the uncrossed depth bias is a power law function of contrast, it is constant with respect to disparity. In a second series of experiments, the contrast dependence of stereo increment thresholds was measured. Like perceived depth and stereoacuity, stereo increment thresholds were found to be a power law function of contrast. These results suggest that contrast effects occur at or before the extraction of depth and have implications for the response properties of disparity-selective mechanisms. (+info)
(4/810) Occlusion contributes to temporal processing differences between crossed and uncrossed stereopsis in random-dot displays.
Stereoscopic depth discrimination was investigated in crossed and uncrossed directions using stimuli defined by binocular disparity differences embedded in dynamic random-dot stereograms. Across three experiments, fixation was directed to a point on the display screen (which placed crossed stimuli in front of and uncrossed stimuli behind, the background dots of the stereogram), to a point in front of the display screen (which placed both crossed and uncrossed stimuli in front of the background dots), and to a point behind the display screen (which placed both crossed and uncrossed stimuli behind the background dots). Results showed that depth discrimination was always good when the stimuli appeared in front of the background dots of the stereogram, whereas discrimination was always poor when the stimuli appeared behind the background dots. These results suggest that differences between crossed and uncrossed stereopsis as reported in past research arose, in part, from effects related to occlusion. (+info)
(5/810) Disconjugate adaptation of saccades: contribution of binocular and monocular mechanisms.
We studied the effects of prism-induced disparity on static and intrasaccadic alignment in six normal human subjects. A ten diopter base-out prism, calling for convergence, was placed in front of the central field of the right eye, so that at the center the eye viewed through the prism; at left and right, outside the prism. During 15 min of training, subjects made repetitive saccades solely in the right field of vision (C-R-C sequence). This paradigm required relative divergence for centrifugal (C-R) saccades and relative convergence for centripetal (R-C) saccades, as well as increase of the amplitude for all saccades made by the right eye. We found that during training, all subjects incorporated the necessary change in alignment into the saccades. After training the resultant intrasaccadic disconjugacy persisted when tested during monocular viewing, indicating that motor learning had occurred. Subjects demonstrated increased divergence for C-R and increased convergence for R-C saccades, in accordance with the change acquired during adaptation to the prism. In addition, five subjects developed increased divergence for C-L saccades, for which they did not train. Smaller and less consistent divergence was also observed for L-C saccades. Changes in intrasaccadic alignment were accompanied by changes in the relative velocities of the two eyes' saccades and slowing of the peak velocities in both eyes during training. Static alignment showed a general tendency toward convergence that did not parallel the changes in the intrasaccadic alignment, suggesting that saccade adaptation is system-specific. The pattern of transfer of the intrasaccadic disconjugacy to saccades in the untrained field and the changes in the relative speeds of the two eyes cannot be explained by monocular adjustment of the saccades. Our results indicate that both a binocular mechanism--saccade-vergence interaction--and monocular adaptation contribute to disconjugate adaptation of saccades. (+info)
(6/810) The extrinsic/intrinsic classification of two-dimensional motion signals with barber-pole stimuli.
The perceived direction of different barber-pole stimuli was assessed by adjusting an arrow on the screen. The terminator ratio (TR: number of terminators moving along the long side divided by the number of terminators moving along the small side) was either one or three. In this latter case, the aperture orientation was either vertical or horizontal. The grating was either in the same plane as the aperture (intrinsic condition) or behind the aperture--the frame containing the aperture had a crossed disparity relative to the grating--(extrinsic condition). A nested design with 120 observers was used for the whole study. Five grating orientations were intermingled within any session. With a terminator ratio of three, the results depend strongly on the aperture's orientation. When the rectangular aperture is horizontal, the perceived direction of an intrinsic grating is horizontal (the typical barber-pole illusion), whereas it is only slightly biased towards orthogonal one-dimensional (1D) motion signals (Vp) in the extrinsic condition. When the aperture is vertical, the perceived direction in the intrinsic condition is largely biased toward Vp, and on average it is close to Vp in the extrinsic condition. In this latter case, however, analysing the distributions of responses shows that many responses do not lie around Vp but are clustered near vertical or horizontal. This motion capture depends on the grating's orientation. With a terminator ratio of one, motion capture is present in both the extrinsic and intrinsic conditions. Moreover, a global bias toward horizontal is observed: this horizontal bias is much larger in the extrinsic condition. Altogether, these results suggest that binocular disparity alone is a weak determinant of the extrinsic/intrinsic classification of two-dimensional (2D) motion signals compared to the occlusion cues provided by unpaired regions in binocular images. Second, truly extrinsic 2D motion signals are not suppressed but rather actively compete against each other to capture the 1D motion signals. This results in a perceptual multistability which is much stronger with extrinsic signals. Finally, given the inherent multistability of barber-pole stimuli, high-level factors can alter the strength of this competition and prime any of the 2D motion signals. (+info)
(7/810) Global motion processing is not tuned for binocular disparity.
An important goal of the visual system is the segmentation of image features into objects and their backgrounds. A primary cue for this is motion: when a region shares the same pattern of motion it is segregated from its surround. Three experiments were carried out to investigate whether the segmentation of image features on the basis of motion information is facilitated by the addition of binocular disparity. Coherence thresholds were measured for the discrimination of the global direction of motion of random dot kinematograms (RDKs) in which the relative disparity of the signal and noise dots was manipulated. When the signal dots were embedded in a three dimensional cloud of noise dots, coherence thresholds were similar to those measured when signal and noise dots were both presented with zero disparity. However, when the signal dots were separated from the noise dots in depth, global motion processing was strongly facilitated. These results were considered in terms of two models, one in which global motion is processed by disparity tuned mechanisms, the other in which the discrimination of the direction of motion is mediated by an attention-based system. It was concluded that global motion processing is not tuned for binocular disparity and that the facilitation of the discrimination of direction provided by binocular disparity in certain circumstances reflects the role of an attention-based system. (+info)
(8/810) Perceived distance, shape and size.
If distance, shape and size are judged independently from the retinal and extra-retinal information at hand, different kinds of information can be expected to dominate each judgement, so that errors in one judgement need not be consistent with errors in other judgements. In order to evaluate how independent these three judgments are, we examined how adding information that improves one judgement influences the others. Subjects adjusted the size and the global shape of a computer-simulated ellipsoid to match a tennis ball. They then indicated manually where they judged the simulated ball to be. Adding information about distance improved the three judgements in a consistent manner, demonstrating that a considerable part of the errors in all three judgements were due to misestimating the distance. Adding information about shape that is independent of distance improved subjects' judgements of shape, but did not influence the set size or the manually indicated distance. Thus, subjects ignored conflicts between the cues when judging the shape, rather than using the conflicts to improve their estimate of the ellipsoid's distance. We conclude that the judgements are quite independent, in the sense that no attempt is made to attain consistency, but that they do rely on some common measures, such as that of distance. (+info)