Visual Field Tests: Method of measuring and mapping the scope of vision, from central to peripheral of each eye.Visual Fields: The total area or space visible in a person's peripheral vision with the eye looking straightforward.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.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 Tests: A series of tests used to assess various functions of the eyes.Telescopes: Instruments used to observe distant objects.Glaucoma: 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)Hemianopsia: Partial or complete loss of vision in one half of the visual field(s) of one or both eyes. Subtypes include altitudinal hemianopsia, characterized by a visual defect above or below the horizontal meridian of the visual field. Homonymous hemianopsia refers to a visual defect that affects both eyes equally, and occurs either to the left or right of the midline of the visual field. Binasal hemianopsia consists of loss of vision in the nasal hemifields of both eyes. Bitemporal hemianopsia is the bilateral loss of vision in the temporal fields. Quadrantanopsia refers to loss of vision in one quarter of the visual field in one or both eyes.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.Glaucoma, Open-Angle: Glaucoma in which the angle of the anterior chamber is open and the trabecular meshwork does not encroach on the base of the iris.Ocular Hypertension: A condition in which the intraocular pressure is elevated above normal and which may lead to glaucoma.Optic Nerve Diseases: Conditions which produce injury or dysfunction of the second cranial or optic nerve, which is generally considered a component of the central nervous system. Damage to optic nerve fibers may occur at or near their origin in the retina, at the optic disk, or in the nerve, optic chiasm, optic tract, or lateral geniculate nuclei. Clinical manifestations may include decreased visual acuity and contrast sensitivity, impaired color vision, and an afferent pupillary defect.Visual Cortex: Area of the OCCIPITAL LOBE concerned with the processing of visual information relayed via VISUAL PATHWAYS.Visual Perception: The selecting and organizing of visual stimuli based on the individual's past experience.Evoked Potentials, Visual: The electric response evoked in the cerebral cortex by visual stimulation or stimulation of the visual pathways.Intraocular Pressure: The pressure of the fluids in the eye.Sensory Thresholds: The minimum amount of stimulus energy necessary to elicit a sensory response.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.Reproducibility of Results: The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.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.Exploratory Behavior: The tendency to explore or investigate a novel environment. It is considered a motivation not clearly distinguishable from curiosity.Pattern Recognition, Visual: Mental process to visually perceive a critical number of facts (the pattern), such as characters, shapes, displays, or designs.Behavior, Animal: The observable response an animal makes to any situation.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.Optic Disk: 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.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.Motor Activity: The physical activity of a human or an animal as a behavioral phenomenon.Maze Learning: Learning the correct route through a maze to obtain reinforcement. It is used for human or animal populations. (Thesaurus of Psychological Index Terms, 6th ed)Racquet Sports: Games in which players use a racquet to hit a ball or similar type object.Fixation, Ocular: The positioning and accommodation of eyes that allows the image to be brought into place on the FOVEA CENTRALIS of each eye.Vision, Binocular: The blending of separate images seen by each eye into one composite image.Motion Perception: The real or apparent movement of objects through the visual field.Attention: Focusing on certain aspects of current experience to the exclusion of others. It is the act of heeding or taking notice or concentrating.Eye Movements: Voluntary or reflex-controlled movements of the eye.Space Perception: The awareness of the spatial properties of objects; includes physical space.Optic Chiasm: The X-shaped structure formed by the meeting of the two optic nerves. At the optic chiasm the fibers from the medial part of each retina cross to project to the other side of the brain while the lateral retinal fibers continue on the same side. As a result each half of the brain receives information about the contralateral visual field from both eyes.Vigabatrin: An analogue of GAMMA-AMINOBUTYRIC ACID. It is an irreversible inhibitor of 4-AMINOBUTYRATE TRANSAMINASE, the enzyme responsible for the catabolism of GAMMA-AMINOBUTYRIC ACID. (From Martindale The Extra Pharmacopoeia, 31st 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.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.Electroretinography: Recording of electric potentials in the retina after stimulation by light.Reaction Time: The time from the onset of a stimulus until a response is observed.Brain Mapping: Imaging techniques used to colocalize sites of brain functions or physiological activity with brain structures.Retinal Ganglion Cells: Neurons of the innermost layer of the retina, the internal plexiform layer. They are of variable sizes and shapes, and their axons project via the OPTIC NERVE to the brain. A small subset of these cells act as photoreceptors with projections to the SUPRACHIASMATIC NUCLEUS, the center for regulating CIRCADIAN RHYTHM.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.Anxiety: Feeling or emotion of dread, apprehension, and impending disaster but not disabling as with ANXIETY DISORDERS.Tomography, Optical Coherence: 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.Diagnostic Techniques, Ophthalmological: Methods and procedures for the diagnosis of diseases of the eye or of vision disorders.Sensitivity and Specificity: 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)Vision, Monocular: Images seen by one eye.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)Retinitis Pigmentosa: Hereditary, progressive degeneration of the neuroepithelium of the retina characterized by night blindness and progressive contraction of the visual field.Avoidance Learning: A response to a cue that is instrumental in avoiding a noxious experience.Molluscacides: Agents destructive to snails and other mollusks.Swimming: An activity in which the body is propelled through water by specific movement of the arms and/or the legs. Swimming as propulsion through water by the movement of limbs, tail, or fins of animals is often studied as a form of PHYSICAL EXERTION or endurance.Functional Laterality: Behavioral manifestations of cerebral dominance in which there is preferential use and superior functioning of either the left or the right side, as in the preferred use of the right hand or right foot.Nerve Fibers: 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.Analysis of Variance: A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.Electromagnetic Fields: Fields representing the joint interplay of electric and magnetic forces.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.).Magnetic Resonance Imaging: 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.Optic Neuropathy, Ischemic: Ischemic injury to the OPTIC NERVE which usually affects the OPTIC DISK (optic neuropathy, anterior ischemic) and less frequently the retrobulbar portion of the nerve (optic neuropathy, posterior ischemic). The injury results from occlusion of arterial blood supply which may result from TEMPORAL ARTERITIS; ATHEROSCLEROSIS; COLLAGEN DISEASES; EMBOLISM; DIABETES MELLITUS; and other conditions. The disease primarily occurs in the sixth decade or later and presents with the sudden onset of painless and usually severe monocular visual loss. Anterior ischemic optic neuropathy also features optic disk edema with microhemorrhages. The optic disk appears normal in posterior ischemic optic neuropathy. (Glaser, Neuro-Ophthalmology, 2nd ed, p135)Saccades: An abrupt voluntary shift in ocular fixation from one point to another, as occurs in reading.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Psychomotor Performance: The coordination of a sensory or ideational (cognitive) process and a motor activity.Anti-Anxiety Agents: Agents that alleviate ANXIETY, tension, and ANXIETY DISORDERS, promote sedation, and have a calming effect without affecting clarity of consciousness or neurologic conditions. ADRENERGIC BETA-ANTAGONISTS are commonly used in the symptomatic treatment of anxiety but are not included here.Ophthalmoscopy: Examination of the interior of the eye with an ophthalmoscope.Discrimination (Psychology): Differential response to different stimuli.Tonometry, Ocular: Measurement of ocular tension (INTRAOCULAR PRESSURE) with a tonometer. (Cline, et al., Dictionary of Visual Science, 4th ed)Anaerobic Threshold: The oxygen consumption level above which aerobic energy production is supplemented by anaerobic mechanisms during exercise, resulting in a sustained increase in lactate concentration and metabolic acidosis. The anaerobic threshold is affected by factors that modify oxygen delivery to the tissues; it is low in patients with heart disease. Methods of measurement include direct measure of lactate concentration, direct measurement of bicarbonate concentration, and gas exchange measurements.Ocular Physiological Phenomena: Processes and properties of the EYE as a whole or of any of its parts.Perceptual Disorders: Cognitive disorders characterized by an impaired ability to perceive the nature of objects or concepts through use of the sense organs. These include spatial neglect syndromes, where an individual does not attend to visual, auditory, or sensory stimuli presented from one side of the body.Low Tension Glaucoma: 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.Retinal DiseasesForm Perception: The sensory discrimination of a pattern shape or outline.Occipital Lobe: Posterior portion of the CEREBRAL HEMISPHERES responsible for processing visual sensory information. It is located posterior to the parieto-occipital sulcus and extends to the preoccipital notch.Cues: Signals for an action; that specific portion of a perceptual field or pattern of stimuli to which a subject has learned to respond.Pupil: The aperture in the iris through which light passes.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.Fundus Oculi: The concave interior of the eye, consisting of the retina, the choroid, the sclera, the optic disk, and blood vessels, seen by means of the ophthalmoscope. (Cline et al., Dictionary of Visual Science, 4th ed)Superior Colliculi: The anterior pair of the quadrigeminal bodies which coordinate the general behavioral orienting responses to visual stimuli, such as whole-body turning, and reaching.Blindness, Cortical: Total loss of vision in all or part of the visual field due to bilateral OCCIPITAL LOBE (i.e., VISUAL CORTEX) damage or dysfunction. Anton syndrome is characterized by the psychic denial of true, organic cortical blindness. (Adams et al., Principles of Neurology, 6th ed, p460)Orientation: Awareness of oneself in relation to time, place and person.Fluorescein Angiography: 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.Parietal Lobe: Upper central part of the cerebral hemisphere. It is located posterior to central sulcus, anterior to the OCCIPITAL LOBE, and superior to the TEMPORAL LOBES.Photography: Method of making images on a sensitized surface by exposure to light or other radiant energy.Optic Nerve: 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.Geniculate Bodies: Part of the DIENCEPHALON inferior to the caudal end of the dorsal THALAMUS. Includes the lateral geniculate body which relays visual impulses from the OPTIC TRACT to the calcarine cortex, and the medial geniculate body which relays auditory impulses from the lateral lemniscus to the AUDITORY CORTEX.Tomography: Imaging methods that result in sharp images of objects located on a chosen plane and blurred images located above or below the plane.Flicker Fusion: The point or frequency at which all flicker of an intermittent light stimulus disappears.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.Pyrethrins: The active insecticidal constituent of CHRYSANTHEMUM CINERARIIFOLIUM flowers. Pyrethrin I is the pyretholone ester of chrysanthemummonocarboxylic acid and pyrethrin II is the pyretholone ester of chrysanthemumdicarboxylic acid monomethyl ester.ReadingVisually Impaired Persons: Persons with loss of vision such that there is an impact on activities of daily living.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.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)Rats, Wistar: A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.Papilledema: Swelling of the OPTIC DISK, usually in association with increased intracranial pressure, characterized by hyperemia, blurring of the disk margins, microhemorrhages, blind spot enlargement, and engorgement of retinal veins. Chronic papilledema may cause OPTIC ATROPHY and visual loss. (Miller et al., Clinical Neuro-Ophthalmology, 4th ed, p175)Magnetic Fields: Areas of attractive or repulsive force surrounding MAGNETS.Refractive Errors: Deviations from the average or standard indices of refraction of the eye through its dioptric or refractive apparatus.Sensory Deprivation: The absence or restriction of the usual external sensory stimuli to which the individual responds.Cats: The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)Dark Adaptation: Adjustment of the eyes under conditions of low light. The sensitivity of the eye to light is increased during dark adaptation.Optic Neuritis: Inflammation of the optic nerve. Commonly associated conditions include autoimmune disorders such as MULTIPLE SCLEROSIS, infections, and granulomatous diseases. Clinical features include retro-orbital pain that is aggravated by eye movement, loss of color vision, and contrast sensitivity that may progress to severe visual loss, an afferent pupillary defect (Marcus-Gunn pupil), and in some instances optic disc hyperemia and swelling. Inflammation may occur in the portion of the nerve within the globe (neuropapillitis or anterior optic neuritis) or the portion behind the globe (retrobulbar neuritis or posterior optic neuritis).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.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.Insecticides: Pesticides designed to control insects that are harmful to man. The insects may be directly harmful, as those acting as disease vectors, or indirectly harmful, as destroyers of crops, food products, or textile fabrics.Running: An activity in which the body is propelled by moving the legs rapidly. Running is performed at a moderate to rapid pace and should be differentiated from JOGGING, which is performed at a much slower pace.Automobile Driving: The effect of environmental or physiological factors on the driver and driving ability. Included are driving fatigue, and the effect of drugs, disease, and physical disabilities on driving.Color Vision: Function of the human eye that is used in bright illumination or in daylight (at photopic intensities). Photopic vision is performed by the three types of RETINAL CONE PHOTORECEPTORS with varied peak absorption wavelengths in the color spectrum (from violet to red, 400 - 700 nm).Pupil Disorders: Conditions which affect the structure or function of the pupil of the eye, including disorders of innervation to the pupillary constrictor or dilator muscles, and disorders of pupillary reflexes.Neurons: The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.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.Memory: Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.Disease Progression: 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.Macula Lutea: 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)Image Processing, Computer-Assisted: 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.Depth Perception: Perception of three-dimensionality.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)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)Corticosterone: An adrenocortical steroid that has modest but significant activities as a mineralocorticoid and a glucocorticoid. (From Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed, p1437)Field Dependence-Independence: The ability to respond to segments of the perceptual experience rather than to the whole.Dominance, Cerebral: Dominance of one cerebral hemisphere over the other in cerebral functions.Glaucoma, Angle-Closure: 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.Macaca: A genus of the subfamily CERCOPITHECINAE, family CERCOPITHECIDAE, consisting of 16 species inhabiting forests of Africa, Asia, and the islands of Borneo, Philippines, and Celebes.Optic Atrophy: Atrophy of the optic disk which may be congenital or acquired. This condition indicates a deficiency in the number of nerve fibers which arise in the RETINA and converge to form the OPTIC DISK; OPTIC NERVE; OPTIC CHIASM; and optic tracts. GLAUCOMA; ISCHEMIA; inflammation, a chronic elevation of intracranial pressure, toxins, optic nerve compression, and inherited conditions (see OPTIC ATROPHIES, HEREDITARY) are relatively common causes of this condition.Trabeculectomy: Any surgical procedure for treatment of glaucoma by means of puncture or reshaping of the trabecular meshwork. It includes goniotomy, trabeculectomy, and laser perforation.Optical Illusions: An illusion of vision usually affecting spatial relations.Size Perception: The sensory interpretation of the dimensions of objects.Eye Diseases: Diseases affecting the eye.Follow-Up Studies: 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.Phosphenes: A subjective visual sensation with the eyes closed and in the absence of light. Phosphenes can be spontaneous, or induced by chemical, electrical, or mechanical (pressure) stimuli which cause the visual field to light up without optical inputs.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.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.

Test-retest variability of frequency-doubling perimetry and conventional perimetry in glaucoma patients and normal subjects. (1/1026)

PURPOSE: To compare the test-retest variability characteristics of frequency-doubling perimetry, a new perimetric test, with those of conventional perimetry in glaucoma patients and normal control subjects. METHODS: The study sample contained 64 patients and 47 normal subjects aged 66.16+/-11.86 and 64.26+/-7.99 years (mean +/- SD), respectively. All subjects underwent frequency-doubling perimetry (using the threshold mode) and conventional perimetry (using program 30-2 of the Humphrey Field Analyzer; Humphrey Instruments, San Leandro, CA) in one randomly selected eye. Each test was repeated at 1-week intervals for five tests with each technique over 4 weeks. Empirical 5th and 95th percentiles of the distribution of threshold deviations at retest were determined for all combinations of single tests and mean of two tests, stratified by threshold deviation. The influence of visual field eccentricity and overall visual field loss on variability also were examined. RESULTS: Mean test time with frequency-doubling perimetry in patients and normal control subjects was 5.90 and 5.25 minutes, respectively, and with conventional perimetry was 17.20 and 14.01 minutes, respectively. In patients, there was a significant correlation between the results of the two techniques, in the full field and in quadrants, whereas in normal subjects there was no such correlation. In patients, the retest variability of conventional perimetry in locations with 20-dB loss was 120% (single tests) and 127% (mean tests) higher compared with that in locations with 0-dB loss. Comparative figures for frequency-doubling perimetry were 40% and 47%, respectively. Variability also increased more with threshold deviation in normal subjects tested with conventional perimetry. In both patients and normal subjects, variability increased with visual field eccentricity in conventional perimetry, but not in frequency-doubling perimetry. Both techniques showed an increase in variability with overall visual field damage. CONCLUSIONS: Frequency-doubling perimetry has different test-retest variability characteristics than conventional perimetry and may have potential for monitoring glaucomatous field damage.  (+info)

Between-algorithm, between-individual differences in normal perimetric sensitivity: full threshold, FASTPAC, and SITA. Swedish Interactive Threshold algorithm. (2/1026)

PURPOSE: To determine the between-algorithm differences in perimetric sensitivity for the Swedish Interactive Threshold algorithm (SITA) Standard, SITA Fast, FASTPAC, and Full Threshold algorithms; to determine the between-subject, between-algorithm differences in the magnitude of the normal variation in sensitivity. METHODS: The sample comprised 50 normal subjects (mean age, 52.9 +/- 18.5 years) experienced in automated perimetry. One randomly assigned eye was examined at three visits with Program 30-2 of the Humphrey Field Analyzer (HFA). The first visit was a familiarization session. A two-period crossover design with order randomization within visits was used over the second and third visits. SITA Standard, SITA Fast, and HFA 640 Full Threshold were administered during one visit. FASTPAC and HFA 750 Full Threshold were administered during the remaining visit. RESULTS: Group mean Mean Sensitivity was 0.8 dB higher for SITA Standard than for Full Threshold (P < 0.001) and 1.3 dB higher for SITA Fast than for Full Threshold (P < 0.001). A similar trend was found between SITA and FASTPAC. The group mean Mean Sensitivity for SITA Fast was 0.5 dB higher than for SITA Standard (P < 0.001). The pointwise between-algorithm difference in sensitivity was similar for all algorithms. The pointwise between-algorithm, between-subject variability was lower for SITA. The examination durations for SITA Fast and SITA Standard were half those for FASTPAC and Full Threshold; SITA Fast was 41% that of SITA Standard (P < 0.001). CONCLUSIONS: SITA produced marginally higher mean mean sensitivity compared with that of existing algorithms and markedly reduced examination duration. The reduced between-subject variability of SITA should result in narrower confidence limits for definition of normality.  (+info)

Looking behind a pathological blind spot in human retina. (3/1026)

Recent work suggests that dichoptic lateral interactions occur in the region of the visual field of one eye that corresponds to the physiological blind spot in the other eye (Tripathy, S. P., & Levi, D. M. (1994). The two-dimensional shape of spatial interaction zones in the parafovea. Vision Research, 34, 1127-1138.) Here we ask whether dichoptic lateral interactions occur in the region of the visual field of one eye that corresponds to a pathological blind spot, a retinal coloboma in the other eye. To address this question we had the observer report the orientation of a letter 'T' presented within this region in the presence of flanking 'T's presented to the other eye around the coloboma. A large drop in performance was seen due to the flanks, showing the existence of dichoptic lateral interactions in this monocular region. The presence of these dichoptic interactions in a region lacking direct retinal afferents from one eye is consistent with the proposition that long-range horizontal connections of the primary visual cortex mediate these interactions.  (+info)

Does visual sensitivity improve between 5 and 8 years? A study of automated visual field examination. (4/1026)

In 74 normal subjects (62 children aged 5-8 years and 12 adults), we tested the widely-held belief that visual sensitivity improves substantially during childhood. Maturation of the retino-striate pathways is generally invoked to account for age-related changes in visual sensitivity. We evaluated the extent to which attentional factors unduly emphasized the effect of age on the purely physiological mechanisms. After a specially-designed familiarization procedure, sensitivity was fully evaluated at two locations in the superior temporal field using a bracketing technique (Octopus 2000R). False-positive (FP) and false-negative (FN) catch-trials were interspersed with the sequence of stimuli. Analyses demonstrated that: (1) age affected sensitivity; and (2) the general level of attentiveness varied not only with age, but also among subjects in the same age group. We then estimated the extent to which improved visual sensitivity may reflect a concomitant evolution of vigilance. Firstly, controlled variance analyses indicated that factors for evaluating attentiveness (rate of FN responses, slope of the psychometric function at the median, and goodness of fit) were indeed much better predictors than age of the sensitivity measured. Secondly and more significantly, the grouping of subjects into homogeneous subgroups, on the basis of their attentional performance, showed that children as young as 5 years may have a visual sensitivity that is only marginally lower than that of adults.  (+info)

Models for the description of angioscotomas. (5/1026)

To describe small scotomas in visual field examinations several statistical models are proposed and applied to the evaluation of angioscotoma in 13 ophthalmologically normal subjects. A special perimetric grid is used where thresholds can be estimated along a line of narrow-spaced test points which crosses the predicted location of the retinal vessel. A two-stage analysis employs single estimations to fit a threshold curve by means of a special parametric description of the luminance difference sensitivity threshold as a function of stimulus position. An alternative model incorporates the threshold as a function of position into the probabilistic description of the binary response (stimulus seen/not seen).  (+info)

Angioscotoma detection with fundus-oriented perimetry. A study with dark and bright stimuli of different sizes. (6/1026)

Fundus-oriented perimetry (FOP) was used to evaluate the effectiveness of different-sized bright and dark stimuli in detecting and quantitatively measuring angioscotoma. The foveolas and optic disks of digitized fundus images were aligned with their psychophysical counterparts to construct individual grids of perimetric stimuli. Each grid included a linear set of test point locations crossing a retinal vessel. Angioscotomas immediately became visible in nine of 13 healthy normal volunteers tested with FOP. Additional mathematical processing of local loss of differential light sensitivity (dls) disclosed an angioscotoma for at least one stimulus condition in all persons tested. The angioscomas were usually deeper for small (12) targets than for large (32') ones. On the other hand, the overall noise at dls thresholds was generally higher for small than for large stimuli regardless of whether the stimuli were bright or dark. No noteworthy differences were found in detection rates or signal-to-noise ratios under different stimulus conditions (dark/bright/small/large). FOP permits the individual arrangement of stimuli for specific morphological conditions and is thus capable of detecting even minute visual field defects such as angioscotomas.  (+info)

Preperimetric glaucoma diagnosis by confocal scanning laser tomography of the optic disc. (7/1026)

AIM: To evaluate the ability of confocal scanning laser tomography of the optic nerve head to detect glaucomatous optic nerve damage in ocular hypertensive eyes without visual field defects. METHODS: The study included 50 normal subjects, 61 glaucoma patients with glaucomatous changes in the optic disc and visual field, and 102 "preperimetric" patients with increased intraocular pressure, normal visual fields, and glaucomatous appearance of the optic disc as evaluated on colour stereo optic disc photographs. For all individuals, confocal scanning laser tomographs of the optic nerve head were taken using the Heidelberg retina tomograph (HRT; software 2.01). RESULTS: Almost all investigated HRT variables varied significantly (p < 0.05) between the normal eyes and preperimetric glaucoma eyes with pronounced overlap between the two study groups. Corresponding to the overlap, sensitivity and specificity values were relatively low when HRT variables were taken to differentiate between normal and preperimetric glaucoma eyes. At a given specificity of 95% highest sensitivities were found for the variables "rim area in the superior disc sector" (24.8%), "nerve fibre layer thickness in the inferior disc sector" (26.5%), and "rim volume in the superior disc sector" (25.5%). A multivariate approach increased sensitivity to 42.2% at a given specificity of 95%. For the glaucoma group highest sensitivity values were reached by rim volume in the superior disc sector (73.8%) and rim area (72.1%); the multivariate approach reached 83.6%. CONCLUSIONS: Owing to pronounced overlapping between the groups, confocal scanning laser tomography of the optic nerve head has relatively low diagnostic power to differentiate between normal eyes and preperimetric glaucoma eyes. One of the reasons may be the biological interindividual variability of quantitative optic disc variables.  (+info)

Measurement of retinal nerve fibre layer by scanning laser polarimetry and high pass resolution perimetry in normal tension glaucoma with relatively high or low intraocular pressure. (8/1026)

AIMS: To determine whether any differences may exist in the relation between the neural capacity as determined by high pass resolution perimetry and the thickness of the retinal nerve fibre layer (RNFL) in patients having normal tension glaucoma (NTG) with a relatively high intraocular pressure (IOP) between 16 and 21 mm Hg (HNTG) v those with a lower IOP below 15 mm Hg (LNTG). METHODS: Scanning laser polarimetry and high pass resolution perimetry were performed in 20 eyes of 20 patients with HNTG and 21 eyes of 21 patients with LNTG. The correlation between total and regional thickness of the peripapillary RNFL and the corresponding total and regional neural capacity with linear regression analysis were evaluated. RESULTS: Overall, although the total RNFL thickness was not significantly correlated with the total neural capacity, the RNFL thickness in each of the superior and inferior quadrants was significantly correlated with the corresponding regional neural capacity (r = 0.44, p = 0.0045; r = 0.39, p = 0.0126 for each). The RNFL thickness in each of the superior and inferior quadrants in the HNTG group was significantly correlated with the corresponding regional neural capacity (r = 0.52, p = 0.0196; r = 0.49, p = 0.0286 for each). No significant correlation between neural capacity and the RNFL thickness was observed either globally or regionally in the LNTG group. CONCLUSION: The degree of the correlation between neural capacity as determined by high pass resolution perimetry and thickness of the RNFL as measured by scanning laser polarimetry appeared to differ in NTG patients with an IOP higher than 15 mm Hg v those with a lower IOP.  (+info)

  • Because of smaller inter-subject variance, shallower depressions are needed in SITA fields for statistical and clinical significance. (
  • Two phases in this study determined preference of perimetry programs for detection of visual field loss in four common neurological conditions (idiopathic intracranial hypertension (IIH), optic neuropathies, chiasmal compression and stroke), to aid the design of research and clinical practice guidelines. (
  • Recommendations currently exist for visual field assessment in glaucoma but not for neurological conditions (National Institute for Health and Clinical Excellence 2009). (
  • METHODS: Data from 330 eyes of 330 normal subjects were collected at 10 centres in order to establish limits of normality for the new SITA strategies and thus, to make it possible to subject SITA fields to computer-assisted visual field analysis. (
  • Your doctor may want you to repeat the test to see if the results are the same the next time you take it. (
  • It is hypothesized that performing VF measurements with a Virtual Reality headset using similar testing strategies as implemented in conventional perimeters, allow for a non-inferior quality in VF acquisitions. (
  • Read on as we walk you through the specifics of coding the most common diagnostic tests for optometry offices. (
  • In refraction, the examiner "determines the prescription required for the eyeglasses or contact lenses by evaluating the effectiveness of a series of lenses through which the patient is asked to view a series of charts," says Becky Shimanek, CPC , coding manager for Aviacode, who led a seminar on "Ophthalmic Diagnostic Tests" at the recent CodingCon 2015 conference. (
  • If the condition is suspected, diagnostic tests are prescribed. (
  • Documentation of diagnostic tests, and the medical rationale for them, is key to reimbursement so we describe the required elements in detail. (
  • The ophthalmologist may do a number of diagnostic tests. (
  • Goldmann or Humphrey visual-field assessment was abnormal only in patient 1, who demonstrated bilaterally enlarged blind spots at diagnosis and later developed reduced sensitivity in the inferomedial quadrant of the left eye in an arcuate pattern (which later resolved). (
  • Known worldwide for our leading technological advancements, M&S is dedicated to bringing high quality, extremely accurate testing products to eye-care professionals, optometry schools and universities. (
  • In the last issue of Optometry Coding & Billing Alert , we gave you a refresher of the general rules and guidelines for ophthalmic tests (see "Part I: Get to the Basics on Diagnostic Test Coding" in Optometry Coding & Billing Alert Vol. 18, No. 2). (
  • Eye Doctors & Optometrists at Chan Optometry offers Visual Field Services and other Optometry Services across Markham , Richmond Hill , Vaughan , Stouffville , Aurora , Newmarket , North York , and Scarborough . (
  • Dr B is Assistant Clinical Professor at the Southern California College of Optometry (SCCO), and is always involved with hands-on training in the field of refractive surgery management. (
  • Thus the oral glucose tolerance test is a reliable method for confirming a diagnosis of Acromegaly. (
  • diagnosis codes are from ICD-10-CM. Documentation of a diagnostic test, and whether there is medical rationale for it, are key to reimbursement so we describe the required elements in detail. (
  • Because the code descriptor specifies "unilateral or bilateral," you would report this code only once whether the optometrist tested one or both eyes. (
  • 2 A literature search found brief details of one other case of bilateral field constriction apparently induced by vigabatrin. (
  • 3. Avoid billing for reduced services when you perform an inherently bilateral test on only one eye. (
  • Conclusions: The present study resulted in a screening grid consisting of 26 locations predominantly testing nasal, superior and inferior areas of the visual field. (
  • The new MRF Visual Field Tablet is meticulously designed and calibrated to deliver consistent results. (
  • Point-by-point comparison between the results obtained with the different modalities indicates: (1) minimal systematic differences between measurements taken in visual grasp and manual modes, (2) the average standard deviation of the difference distributions of about 5 dB, and (3) a systematic shift (of 4-6 dB) to lower sensitivities for VirtualEye device, observed mostly in high dB range. (
  • Does Lowering Eye Pressure Affect the Results Obtained From Objective Visual Field Testing? (
  • The purpose of this study is to evaluate the suitable visual field (VF) test conditions (target size, test type, and eccentricity) for the macular region, we investigated the correlations between the ganglion cell layer (GCL) thickness and 6 VF test results. (
  • VFs can exhibit extensive measurement error and it is widely accepted that clinical management decisions made on results from one or two tests will as a rule be unsound. (
  • Although the results for movement effects on cognitive load in this experiment were not statistically significant, men spent less time on the cognitive test in the peripheral movement condition than in the conditions without peripheral movement. (
  • The DVLA banned over 600 motorists from driving following tests carried out by government appointed optometrists, but the DVLA now admits that the test results were false. (
  • Results obtained from the test are compared to what is known about visual field tests in normal eyes. (
  • There are well-known patterns in the test results that help us recognize certain types of injury or disease. (
  • This includes automated eye tracking, which can analyse pupil movement for increased reliability of test results. (
  • What's more, the machine offers blink control whereby the test is put on hold to ensure normal blinking does not affect visual performance or the results. (
  • Using the results of these tests, your doctor will be able to determine if you are having trouble seeing in certain areas of your visual field, as well as possible causes for these difficulties. (
  • Your eye doctor may have you repeat the test or have additional testing depending on the results. (
  • The results of this test are largely dependent on the test taker. (
  • At the end of the lecture optometrists will have a better understanding of testing and interpreting visual field results. (
  • Blood tests, including mitochondrial DNA screen and measurement of phytanic acid and lysosomal enzyme concentrations, gave normal results. (
  • Blood test results, as for case 1, were normal. (
  • Visual fields were concentrically constricted in both eyes (fig 1 (bottom)), but funduscopy and fluorescein angiography gave normal results. (
  • electrodiagnostic test results were otherwise normal. (
  • The new rules outlined clear for not only which visual field testing method was to be used, but also how the results should be interpreted and assessed, and guidelines for doctors to report drivers not fulfilling the requirements. (
  • These results demonstrate large-scale reorganization of visual processing in MD and will likely prove important in any effort to develop new strategies for rehabilitation of MD subjects. (
  • These results demonstrate large-scale reorganization of visual processing in humans with MD. (
  • Simple manual equipment can be used such as in the tangent screen test or the Amsler grid. (
  • Doctors have access to a whole range of tests that help diagnose and monitor age-related macular degeneration. (
  • In just the past few decades, the variety and sophistication of the ways we test for age-related macular degeneration (AMD) have grown tremendously. (
  • It also gives the mean deviation or overall depression or elevation of the visual field when compared to a reference field. (
  • Parameters including age, sex, axial length, central corneal thickness, IOP before the VF test, the VF index, mean deviation, VF test duration, and usage of IOP lowering medications were investigated, and the correlations of these parameters with IOP changes after VF tests were determined using linear regression analyses. (
  • The average RNFL thickness of the inferior and superior disc sectors was plotted against the average total deviations (linear units) of the corresponding superior and inferior arcuate field regions, and a linear model was fitted. (
  • The physiological basis of this test is a decrease in adrenocorticotropic hormone (ACTH) secretion by the pituitary because of exogenous glucocorticoid administration. (
  • A particular type of brain cell--the quasi-visual (QV) neuron--is assumed to play an important role in this updating by combining target coordinates and eye displacement signals. (
  • Some eye and brain disorders are responsible for these visual field def. (
  • This is the back portion of the eye that receives light coming into the eye, and sends that visual information to the brain. (
Static perimetry approach may be better for kids with glaucoma
Static perimetry approach may be better for kids with glaucoma (
Visual field test simulation and error in threshold estimation. | British Journal of Ophthalmology
Visual field test simulation and error in threshold estimation. | British Journal of Ophthalmology (
How is Acromegaly Diagnosed?
How is Acromegaly Diagnosed? (
Visual Field Test With Automated Perimetry | Virtual Visual Field
Visual Field Test With Automated Perimetry | Virtual Visual Field (
Clinical notes
Clinical notes (
Optic glioma: MedlinePlus Medical Encyclopedia
Optic glioma: MedlinePlus Medical Encyclopedia (
Medicaid | Administrative Claims Records | Information on Data Sources | Vision and Eye Health Surveillance System | Vision...
Medicaid | Administrative Claims Records | Information on Data Sources | Vision and Eye Health Surveillance System | Vision... (
Pituitary Tumors Workup: Laboratory Studies, Imaging Studies, Other Tests
Pituitary Tumors Workup: Laboratory Studies, Imaging Studies, Other Tests (
Non-inferiority Study for Visual Field Measurements Using a Virtual Reality Device - Full Text View -
Non-inferiority Study for Visual Field Measurements Using a Virtual Reality Device - Full Text View - (
Choosing Wisely When It Comes to Eye Care, Part 2 - American Academy of Ophthalmology
Choosing Wisely When It Comes to Eye Care, Part 2 - American Academy of Ophthalmology (
Visual Impairment
Visual Impairment (
How to Test Peripheral Vision (with Pictures) - wikiHow
How to Test Peripheral Vision (with Pictures) - wikiHow (
Visual Field Test Center by
Visual Field Test Center by (
Retinal degeneration and ageing
Retinal degeneration and ageing (
President Bush Sails Through Annual Physical | Medpage Today
President Bush Sails Through Annual Physical | Medpage Today (
Glaucoma-landing-page - Medical Technology | ZEISS International
Glaucoma-landing-page - Medical Technology | ZEISS International (
Ophthalmology Services | Rush System
Ophthalmology Services | Rush System (
Eye surgery and treatments | Spire Dunedin Hospital, Reading, Berkshire
Eye surgery and treatments | Spire Dunedin Hospital, Reading, Berkshire (
Interpreting Visual Fields - English
Interpreting Visual Fields - English (
Platelet-RBC interaction mediated by FasL/FasR induces procoagulant activity important for thrombosis
JCI - Platelet-RBC interaction mediated by FasL/FasR induces procoagulant activity important for thrombosis (
Mr Vincent Dubois</span><i class=icon aria-hidden=...
Mr Vincent Dubois</span><i class="icon" aria-hidden=... (