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.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.Vision Tests: A series of tests used to assess various functions of the eyes.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)Sensory Thresholds: The minimum amount of stimulus energy necessary to elicit a sensory response.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.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).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.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.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, Ocular: The process in which light signals are transformed by the PHOTORECEPTOR CELLS into electrical signals which can then be transmitted to the brain.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.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.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.Visual Fields: The total area or space visible in a person's peripheral vision with the eye looking straightforward.Pattern Recognition, Visual: Mental process to visually perceive a critical number of facts (the pattern), such as characters, shapes, displays, or designs.Space Perception: The awareness of the spatial properties of objects; includes physical space.Flicker Fusion: The point or frequency at which all flicker of an intermittent light stimulus disappears.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.Evoked Potentials, Visual: The electric response evoked in the cerebral cortex by visual stimulation or stimulation of the visual pathways.Form Perception: The sensory discrimination of a pattern shape or outline.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)Orthoptics: The study and treatment of defects in binocular vision resulting from defects in the optic musculature or of faulty visual habits. It involves a technique of eye exercises designed to correct the visual axes of eyes not properly coordinated for binocular vision.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)Pupil: The aperture in the iris through which light passes.Vision, Binocular: The blending of separate images seen by each eye into one composite image.Color Perception Tests: Type of vision test used to determine COLOR VISION DEFECTS.Myopia: A refractive error in which rays of light entering the EYE parallel to the optic axis are brought to a focus in front of the RETINA when accommodation (ACCOMMODATION, OCULAR) is relaxed. This results from an overly curved CORNEA or from the eyeball being too long from front to back. It is also called nearsightedness.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).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)Lenses, Intraocular: Artificial implanted lenses.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)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.).Discrimination (Psychology): Differential response to different stimuli.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.Visual Field Tests: Method of measuring and mapping the scope of vision, from central to peripheral of each eye.Optics and Photonics: A specialized field of physics and engineering involved in studying the behavior and properties of light and the technology of analyzing, generating, transmitting, and manipulating ELECTROMAGNETIC RADIATION in the visible, infrared, and ultraviolet range.Visual Perception: The selecting and organizing of visual stimuli based on the individual's past experience.Nystagmus, Optokinetic: Normal nystagmus produced by looking at objects moving across the field of vision.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.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.Keratomileusis, Laser In Situ: A surgical procedure to correct MYOPIA by CORNEAL STROMA subtraction. It involves the use of a microkeratome to make a lamellar dissection of the CORNEA creating a flap with intact CORNEAL EPITHELIUM. After the flap is lifted, the underlying midstroma is reshaped with an EXCIMER LASER and the flap is returned to its original position.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.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.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).Orientation: Awareness of oneself in relation to time, place and person.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.Refraction, Ocular: Refraction of LIGHT effected by the media of the EYE.Macaca nemestrina: A species of the genus MACACA which inhabits Malaya, Sumatra, and Borneo. It is one of the most arboreal species of Macaca. The tail is short and untwisted.Refractive Errors: Deviations from the average or standard indices of refraction of the eye through its dioptric or refractive apparatus.Vision, Monocular: Images seen by one eye.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)Motion Perception: The real or apparent movement of objects through the visual field.Visual Cortex: Area of the OCCIPITAL LOBE concerned with the processing of visual information relayed via VISUAL PATHWAYS.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.Ocular Physiological Phenomena: Processes and properties of the EYE as a whole or of any of its parts.Light: That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.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.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)Dyslexia: A cognitive disorder characterized by an impaired ability to comprehend written and printed words or phrases despite intact vision. This condition may be developmental or acquired. Developmental dyslexia is marked by reading achievement that falls substantially below that expected given the individual's chronological age, measured intelligence, and age-appropriate education. The disturbance in reading significantly interferes with academic achievement or with activities of daily living that require reading skills. (From DSM-IV)Visually Impaired Persons: Persons with loss of vision such that there is an impact on activities of daily living.Depth Perception: Perception of three-dimensionality.Vision Screening: Application of tests and examinations to identify visual defects or vision disorders occurring in specific populations, as in school children, the elderly, etc. It is differentiated from VISION TESTS, which are given to evaluate/measure individual visual performance not related to a specific population.Anisometropia: A condition of an inequality of refractive power of the two eyes.Fixation, Ocular: The positioning and accommodation of eyes that allows the image to be brought into place on the FOVEA CENTRALIS of each eye.Sensory Deprivation: The absence or restriction of the usual external sensory stimuli to which the individual responds.Aging: The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.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.Fluspirilene: A long-acting injectable antipsychotic agent used for chronic schizophrenia.Photometry: Measurement of the various properties of light.Astigmatism: Unequal curvature of the refractive surfaces of the eye. Thus a point source of light cannot be brought to a point focus on the retina but is spread over a more or less diffuse area. This results from the radius of curvature in one plane being longer or shorter than the radius at right angles to it. (Dorland, 27th ed)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.Contact Lenses: Lenses designed to be worn on the front surface of the eyeball. (UMDNS, 1999)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)Orthokeratologic Procedures: An alternative to REFRACTIVE SURGICAL PROCEDURES. A therapeutic procedure for correcting REFRACTIVE ERRORS. It involves wearing CONTACT LENSES designed to force corrective changes to the curvature of the CORNEA that remain after the lenses are removed. The effect is temporary but is maintained by wearing the therapeutic lenses daily, usually during sleep.Afterimage: Continuation of visual impression after cessation of stimuli causing the original image.Psychophysiology: The study of the physiological basis of human and animal behavior.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.Models, Psychological: Theoretical representations that simulate psychological processes and/or social processes. These include the use of mathematical equations, computers, and other electronic equipment.Aberrometry: The use of an aberrometer to measure eye tissue imperfections or abnormalities based on the way light passes through the eye which affects the ability of the eye to focus properly.EthylaminesCataract Extraction: The removal of a cataractous CRYSTALLINE LENS from the eye.Size Perception: The sensory interpretation of the dimensions of objects.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.Argon: Argon. A noble gas with the atomic symbol Ar, atomic number 18, and atomic weight 39.948. It is used in fluorescent tubes and wherever an inert atmosphere is desired and nitrogen cannot be used.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: The visually perceived property of objects created by absorption or reflection of specific wavelengths of light.Subretinal Fluid: An exudate between the RETINA and CHOROID from various sources including the vitreous cavity, SUBARACHNOID SPACE, or abnormal vessels.Nature: The system of all phenomena in space and time; the totality of physical reality. It is both a scientific and philosophic concept appearing in all historic eras. (Webster 2d; Dr. James H. Cassedy, NLM History of Medicine Division)Presbyopia: The normal decreasing elasticity of the crystalline lens that leads to loss of accommodation.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.Refractive Surgical Procedures: Surgical procedures employed to correct REFRACTIVE ERRORS such as MYOPIA; HYPEROPIA; or ASTIGMATISM. These may involve altering the curvature of the CORNEA; removal or replacement of the CRYSTALLINE LENS; or modification of the SCLERA to change the axial length of the eye.Electroretinography: Recording of electric potentials in the retina after stimulation by light.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Retinal DiseasesDiabetic Retinopathy: Disease of the RETINA as a complication of DIABETES MELLITUS. It is characterized by the progressive microvascular complications, such as ANEURYSM, interretinal EDEMA, and intraocular PATHOLOGIC NEOVASCULARIZATION.Perceptual Masking: The interference of one perceptual stimulus with another causing a decrease or lessening in perceptual effectiveness.ReadingHalogens: A family of nonmetallic, generally electronegative, elements that form group 17 (formerly group VIIa) of the periodic table.Aphakia, Postcataract: Absence of the crystalline lens resulting from cataract extraction.Attention: Focusing on certain aspects of current experience to the exclusion of others. It is the act of heeding or taking notice or concentrating.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)Ophthalmoscopes: Devices for examining the interior of the eye, permitting the clear visualization of the structures of the eye at any depth. (UMDNS, 1999)Injections, Intraocular: The administration of substances into the eye with a hypodermic syringe.Lens Implantation, Intraocular: Insertion of an artificial lens to replace the natural CRYSTALLINE LENS after CATARACT EXTRACTION or to supplement the natural lens which is left in place.Perceptual Distortion: Lack of correspondence between the way a stimulus is commonly perceived and the way an individual perceives it under given conditions.Photorefractive Keratectomy: A type of refractive surgery of the CORNEA to correct MYOPIA and ASTIGMATISM. An EXCIMER LASER is used directly on the surface of the EYE to remove some of the CORNEAL EPITHELIUM thus reshaping the anterior curvature of the cornea.Differential Threshold: The smallest difference which can be discriminated between two stimuli or one which is barely above the threshold.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.Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Eye Diseases: Diseases affecting the eye.Reaction Time: The time from the onset of a stimulus until a response is observed.Melopsittacus: A genus, commonly called budgerigars, in the family PSITTACIDAE. In the United States they are considered one of the five species of PARAKEETS.Pseudophakia: Presence of an intraocular lens after cataract extraction.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.Miotics: Agents causing contraction of the pupil of the eye. Some sources use the term miotics only for the parasympathomimetics but any drug used to induce miosis is included here.Keratotomy, Radial: A procedure to surgically correct REFRACTIVE ERRORS by cutting radial slits into the CORNEA to change its refractive properties.Duane Retraction Syndrome: A syndrome characterized by marked limitation of abduction of the eye, variable limitation of adduction and retraction of the globe, and narrowing of the palpebral fissure on attempted adduction. The condition is caused by aberrant innervation of the lateral rectus by fibers of the OCULOMOTOR NERVE.Retinitis Pigmentosa: Hereditary, progressive degeneration of the neuroepithelium of the retina characterized by night blindness and progressive contraction of the visual field.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.Lasers: An optical source that emits photons in a coherent beam. Light Amplification by Stimulated Emission of Radiation (LASER) is brought about using devices that transform light of varying frequencies into a single intense, nearly nondivergent beam of monochromatic radiation. Lasers operate in the infrared, visible, ultraviolet, or X-ray regions of the spectrum.Psychometrics: Assessment of psychological variables by the application of mathematical procedures.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.Eye: The organ of sight constituting a pair of globular organs made up of a three-layered roughly spherical structure specialized for receiving and responding to light.Esotropia: A form of ocular misalignment characterized by an excessive convergence of the visual axes, resulting in a "cross-eye" appearance. An example of this condition occurs when paralysis of the lateral rectus muscle causes an abnormal inward deviation of one eye on attempted gaze.Ocular Hypertension: A condition in which the intraocular pressure is elevated above normal and which may lead to glaucoma.Cues: Signals for an action; that specific portion of a perceptual field or pattern of stimuli to which a subject has learned to respond.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.Practice (Psychology): Performance of an act one or more times, with a view to its fixation or improvement; any performance of an act or behavior that leads to learning.Keratoconus: A noninflammatory, usually bilateral protrusion of the cornea, the apex being displaced downward and nasally. It occurs most commonly in females at about puberty. The cause is unknown but hereditary factors may play a role. The -conus refers to the cone shape of the corneal protrusion. (From Dorland, 27th ed)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)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)Intraocular Pressure: The pressure of the fluids in the eye.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.Hyperopia: A refractive error in which rays of light entering the eye parallel to the optic axis are brought to a focus behind the retina, as a result of the eyeball being too short from front to back. It is also called farsightedness because the near point is more distant than it is in emmetropia with an equal amplitude of accommodation. (Dorland, 27th ed)AlabamaNeurons: 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.Eye Movements: Voluntary or reflex-controlled movements of the eye.Age 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.Macular Edema: Fluid accumulation in the outer layer of the MACULA LUTEA that results from intraocular or systemic insults. It may develop in a diffuse pattern where the macula appears thickened or it may acquire the characteristic petaloid appearance referred to as cystoid macular edema. Although macular edema may be associated with various underlying conditions, it is most commonly seen following intraocular surgery, venous occlusive disease, DIABETIC RETINOPATHY, and posterior segment inflammatory disease. (From Survey of Ophthalmology 2004; 49(5) 470-90)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.Child Development: The continuous sequential physiological and psychological maturing of an individual from birth up to but not including ADOLESCENCE.Lens, Crystalline: A transparent, biconvex structure of the EYE, enclosed in a capsule and situated behind the IRIS and in front of the vitreous humor (VITREOUS BODY). It is slightly overlapped at its margin by the ciliary processes. Adaptation by the CILIARY BODY is crucial for OCULAR ACCOMMODATION.Cornea: The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous CORNEAL EPITHELIUM; BOWMAN MEMBRANE; CORNEAL STROMA; DESCEMET MEMBRANE; and mesenchymal CORNEAL ENDOTHELIUM. It serves as the first refracting medium of the eye. It is structurally continuous with the SCLERA, avascular, receiving its nourishment by permeation through spaces between the lamellae, and is innervated by the ophthalmic division of the TRIGEMINAL NERVE via the ciliary nerves and those of the surrounding conjunctiva which together form plexuses. (Cline et al., Dictionary of Visual Science, 4th ed)Photoreceptor Cells: Specialized cells that detect and transduce light. They are classified into two types based on their light reception structure, the ciliary photoreceptors and the rhabdomeric photoreceptors with MICROVILLI. Ciliary photoreceptor cells use OPSINS that activate a PHOSPHODIESTERASE phosphodiesterase cascade. Rhabdomeric photoreceptor cells use opsins that activate a PHOSPHOLIPASE C cascade.Retinal Vessels: The blood vessels which supply and drain the RETINA.Diagnostic Techniques, Ophthalmological: Methods and procedures for the diagnosis of diseases of the eye or of vision disorders.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.Rotation: Motion of an object in which either one or more points on a line are fixed. It is also the motion of a particle about a fixed point. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Signal Detection, Psychological: Psychophysical technique that permits the estimation of the bias of the observer as well as detectability of the signal (i.e., stimulus) in any sensory modality. (From APA, Thesaurus of Psychological Index Terms, 8th ed.)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.Case-Control Studies: Studies which start with the identification of persons with a disease of interest and a control (comparison, referent) group without the disease. The relationship of an attribute to the disease is examined by comparing diseased and non-diseased persons with regard to the frequency or levels of the attribute in each group.Laser Coagulation: The use of green light-producing LASERS to stop bleeding. The green light is selectively absorbed by HEMOGLOBIN, thus triggering BLOOD COAGULATION.Choroidal Neovascularization: A pathological process consisting of the formation of new blood vessels in the CHOROID.Scattering, Radiation: The diversion of RADIATION (thermal, electromagnetic, or nuclear) from its original path as a result of interactions or collisions with atoms, molecules, or larger particles in the atmosphere or other media. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Psychomotor Performance: The coordination of a sensory or ideational (cognitive) process and a motor activity.Diagnosis, Computer-Assisted: Application of computer programs designed to assist the physician in solving a diagnostic problem.Action Potentials: Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.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.Postoperative Period: The period following a surgical operation.

Why and how is soft copy reading possible in clinical practice? (1/2967)

The properties of the human visual system (HVS) relevant to the diagnostic process are described after a brief introduction on the general problems and advantages of using soft copy for primary radiology interpretations. At various spatial and temporal frequencies the contrast sensitivity defines the spatial resolution of the eye-brain system and the sensitivity to flicker. The adaptation to the displayed radiological scene and the ambient illumination determine the dynamic range for the operation of the HVS. Although image display devices are determined mainly by state-of-the-art technology, analysis of the HVS may suggest technical characteristics for electronic displays that will help to optimize the display to the operation of the HVS. These include display size, spatial resolution, contrast resolution, luminance range, and noise, from which further consequences for the technical components of a monitor follow. It is emphasized that routine monitor quality control must be available in clinical practice. These image quality measures must be simple enough to be applied as part of the daily routine. These test instructions might also serve as elements of technical acceptance and constancy tests.  (+info)

Impairment in preattentive visual processing in patients with Parkinson's disease. (2/2967)

We explored the possibility of whether preattentive visual processing is impaired in Parkinson's disease. With this aim, visual discrimination thresholds for orientation texture stimuli were determined in two separate measurement sessions in 16 patients with idiopathic Parkinson's disease. The results were compared with those of 16 control subjects age-matched and 16 young healthy volunteers. Discrimination thresholds were measured in a four-alternative spatial forced-choice paradigm, in which subjects judged the location of a target embedded in a background of distractors. Four different stimulus configurations were employed: (i) a group of vertical targets among horizontal distractors ('vertical line targets'); (ii) targets with varying levels of orientation difference on a background of spatially filtered vertically oriented noise ('Gaussian filtered noise'); (iii) one 'L' among 43 '+' signs ('texton'), all of which assess preattentive visual processing; and (iv) control condition, of one 'L' among 43 'T' distractors ('non-texton' search target), which reflects attentive visual processing. In two of the preattentive tasks (filtered noise and texton), patients with Parkinson's disease required significantly greater orientation differences and longer stimulus durations, respectively. In contrast, their performance in the vertical line target and non-texton search target was comparable to that of the matched control subjects. These differences were more pronounced in the first compared with the second session. Duration of illness and age within the patient group correlated significantly with test performance. In all conditions tested, the young control subjects performed significantly better than the more elderly control group, further indicating an effect of age on this form of visual processing. The results suggest that, in addition to the well documented impairment in retinal processing, idiopathic Parkinson's disease is associated with a deficit in preattentive cortical visual processing.  (+info)

Accurate memory for colour but not pattern contrast in chicks. (3/2967)

The visual displays of animals and plants often look dramatic and colourful to us, but what information do they convey to their intended, non-human, audience [1] [2]? One possibility is that stimulus values are judged accurately - so, for example, a female might choose a suitor if he displays a specific colour [3]. Alternatively, as for human advertising, displays may attract attention without giving information, perhaps by exploiting innate preferences for bright colours or symmetry [2] [4] [5]. To address this issue experimentally, we investigated chicks' memories of visual patterns. Food was placed in patterned paper containers which, like seed pods or insect prey, must be manipulated to extract food and their patterns learnt. To establish what was learnt, birds were tested on familiar stimuli and on alternative stimuli of differing colour or contrast. For colour, birds selected the trained stimulus; for contrast, they preferred high contrast patterns over the familiar. These differing responses to colour and contrast show how separate components of display patterns could serve different roles, with colour being judged accurately whereas pattern contrast attracts attention.  (+info)

Characteristics of discrepancies between self-reported visual function and measured reading speed. Salisbury Eye Evaluation Project Team. (4/2967)

PURPOSE: Visual impairment is a risk factor for morbidity in the elderly and is often screened for by self-report. This study evaluates whether there are subsets for whom there is a discrepancy between self-reported and measured function. METHODS: The prevalence of a discrepancy between self-reported difficulty reading a newspaper and measured reading speed was determined in 2520 community-based men and women, aged 65 to 84 years, and the discrepant group characterized by polychotomous regression. RESULTS: Of subjects who reported minimal difficulty reading a newspaper, 10.8% (227/2107) read newsprint-sized text (0.21 degrees) more slowly than 80 words/min, a level previously shown to be necessary for sustained reading. Poor visual acuity, presence of psychiatric symptoms, and less satisfaction with vision were associated with being in the group that read slowly and reported difficulty with reading. Better cognition, better visual acuity, more years of education, white race, and fewer psychiatric symptoms were associated with being in the group that read more quickly and reported minimal difficulty. When reading the text size at which subjects read their fastest, only 2.6% of those with minimal difficulty remained discrepant. These individuals were more likely to have less education, be male, be African American, and have poorer cognitive status than those who did not remain discrepant. CONCLUSIONS: A subset of the elderly population have a substantial discrepancy between self-reported reading difficulty and measured reading speed. In some, this discrepancy may be based on underlying expectations and experiences, and in others it may represent a transition from no visual impairment to visual impairment.  (+info)

Perceived visual ability for independent mobility in persons with retinitis pigmentosa. (5/2967)

PURPOSE: To determine the distribution of perceived ability for independent mobility in people who are at various stages of retinitis pigmentosa (RP). METHODS: A questionnaire was developed to ask subjects to rate how difficult they found each of 35 mobility situations if they had no assistance. The scale was 1 (no difficulty) to 5 (extreme difficulty). In each of 127 subjects, the Rasch analysis, a latent trait analysis, was used to convert the ordinal difficulty ratings into interval measures of perceived visual ability for independent mobility. RESULTS: Content validity of the questionnaire was shown by good separation indexes (4.55 and 8.0) and high reliability scores (0.96 and 0.98) for the person and the item parameters. Construct validity was shown with model fit statistics. Criterion validity of the questionnaire was shown by good discrimination among mobility-related behavior such as "limit independent travel," "always ask for accompaniment," "use a mobility aid," and "have a fear of falling." The mobility situation shown to require the least visual ability was "moving about in the home"; the situation requiring the most was "walking at night." Bivariate regression analysis determined that for every decade of disease progression, perceived visual ability for mobility decreased by approximately 0.5 logit, which was slightly less than 10% of the total range in the study sample. A linear combination of the visual function measures, log minimum angle of resolution, log contrast sensitivity, and log retinal area accounted for 57% of the variability in the person measure. CONCLUSIONS: The patient-based assessment, developed to determine difficulty across a range of mobility situations, is a valid way to measure perceived ability for independent mobility. This latent trait varies systematically with the progression of RP and with visual function measures.  (+info)

Cone signal contributions to electroretinograms [correction of electrograms] in dichromats and trichromats. (6/2967)

PURPOSE: To find out how the different cone types contribute to the electroretinogram (ERG) by quantifying the contribution of the signal pathways originating in the long (L-) and the middle (M-) wavelength-sensitive cones to the total ERG response amplitude and phase. METHODS: ERG response amplitudes and phases were measured to cone-isolating stimuli and to different combinations of L- and M-cone modulation. Conditions were chosen to exclude any contribution of the short wavelength-sensitive (S-) cones. The sensitivity of the ERG to the L and the M cones was defined as the cone contrast gain. RESULTS: In the present paper, a model is provided that describes the ERG contrast gains and ERG thresholds in dichromats and color normal trichromats. For the X-chromosome-linked dichromats, the contrast gains of only one cone type (either the L or the M cones) sufficed to describe the ERG thresholds for all stimulus conditions. Data suggest that the M-cone contrast gains of protanopes are larger than the L-cone contrast gains of deuteranopes. The response thresholds of the trichromats are modeled by assuming a vector summation of signals originating in the L and the M cones. Their L- and M-cone contrast gains are close to a linear interpolation of the data obtained from the dichromats. Nearly all trichromats had larger L- than M-cone contrast gains. Data from a large population of trichromats were examined to study the individual variations in cone weightings and in the phases of the cone pathway responses. CONCLUSIONS: The data strongly suggest that the missing cone type in dichromats is replaced by the remaining cone type. The mean L-cone to M-cone weighting ratio in trichromats was found to be approximately 4:1. But there is a substantial interindividual variability between trichromats. The response phases of the L- and the M-cone pathways can be reliably quantified using the response phases to the cone-isolating stimuli or using a vector addition of L- and M-cone signals.  (+info)

Selective color constancy deficits after circumscribed unilateral brain lesions. (7/2967)

The color of an object, when part of a complex scene, is determined not only by its spectral reflectance but also by the colors of all other objects in the scene (von Helmholtz, 1886; Ives, 1912; Land, 1959). By taking global color information into account, the visual system is able to maintain constancy of the color appearance of the object, despite large variations in the light incident on the retina arising from changes in the spectral content of the illuminating light (Hurlbert, 1998; Maloney, 1999). The neural basis of this color constancy is, however, poorly understood. Although there seems to be a prominent role for retinal, cone-specific adaptation mechanisms (von Kries, 1902; Poppel, 1986; Foster and Nascimento, 1994), the contribution of cortical mechanisms to color constancy is still unclear (Land et al., 1983; D'Zmura and Lennie, 1986). We examined the color perception of 27 patients with defined unilateral lesions mainly located in the parieto-temporo-occipital and fronto-parieto-temporal cortex. With a battery of clinical and specially designed color vision tests we tried to detect and differentiate between possible deficits in central color processing. Our results show that color constancy can be selectively impaired after circumscribed unilateral lesions in parieto-temporal cortex of the left or right hemisphere. Five of 27 patients exhibited significant deficits in a color constancy task, but all of the 5 performed well in color discrimination or higher-level visual tasks, such as the association of colors with familiar objects. These results indicate that the computations underlying color constancy are mediated by specialized cortical circuitry, which is independent of the neural substrate for color discrimination and for assigning colors to objects.  (+info)

Geometric representation of the mechanisms underlying human curvature detection. (8/2967)

Combined manipulation of blur, line length and contrast reveal two distinct processes involved in curvature detection. When line length is small relative to blur, thresholds are almost directly proportional to blur and independent of line length. When line length is large relative to blur thresholds are directly proportional to line length and independent of blur. The aspect ratio (line length/blur) of curved contours represents a scale-invariant metric which forms the decisive factor in determining curvature performance.  (+info)

*Evoked potential

Norcia and Tyler have used the technique to document the development of visual acuity[16][20] and contrast sensitivity[21] ... Norcia A. M.; Tyler C. W.; Allen D. (1986). "Electrophysiological assessment of contrast sensitivity in human infants". ... The resulting plot of stimulus luminance versus wavelength is a plot of the spectral sensitivity of the visual system.[5][18] ...

*Rec. 2020

The NHK measured contrast sensitivity for the Rec. 2020 color space using Barten's equation which had previously been used to ...

*Electrical impedance tomography

"Contrast-enhanced breast MRI: factors affecting sensitivity and specificity". European Radiology. 7: 281-288. doi:10.1007/ ... In contrast, time difference EIT determines relative impedance changes that may be caused by either ventilation or changes of ... In contrast to most other tomographic imaging techniques, EIT does not apply any kind of ionizing radiation. Currents typically ... Kuo, P. H.; Kanal, E.; Abu-Alfa, A. K.; Cowper, S. E. (2007). "Gadolinium-based MR contrast agents and nephrogenic systemic ...

*Lea test

This test uses a series of cards depicting cartoon faces of different contrast levels. The contrast sensitivity assessment ... It is especially vital to assess a child's contrast sensitivity at a young age in order to determine the distance and accuracy ... such as contrast sensitivity, visual field, color vision, visual adaptation, motion perception, and ocular function and ... Contrast sensitivity. Retrieved from http://www.lea-test.fi/en/assessme/educearl/part1/contrast.html Official website Dr. Lea ...

*Binocular summation

... which is the ratio of binocular contrast sensitivity to the contrast sensitivity of the better eye. B S R = C S b i n o c u l a ... Contrast sensitivity. Visual acuity. A practical measure of binocularity is the binocular summation ratio BSR, ... By combining the information received in each eye, binocular summation can improve visual acuity, contrast sensitivity, flicker ... Schrödinger (1926) put forth an equation for binocular brightness and contrast combination where each monocular input is ...

*Aerial perspective

A person's contrast sensitivity function is contrast sensitivity as a function of spatial frequency. Normally, peak contrast ... Contrast sensitivity is the reciprocal of the smallest contrast for which a person can see a sine-wave grating. ... Reducing the contrast of an image reduces the visibility of these high spatial frequencies because contrast sensitivity for ... The ability of a person with normal visual acuity to see fine details is determined by his or her contrast sensitivity. ...

*Bird vision

Contrast sensitivity is the inverse of the smallest contrast that can be detected; a contrast sensitivity of 100 means that the ... A contrast sensitivity function describes an animal's ability to detect the contrast of grating patterns of different spatial ... Birds have comparably lower contrast sensitivity than mammals. Humans have been shown to detect contrasts as low as 0.5-1% ... Spatial luminance contrast sensitivity tests of macaque and human observers". Vision Research. 14 (1): 75-81. doi:10.1016/0042- ...

*Leber's hereditary optic neuropathy

Contrast sensitivity may be diminished. There could be an abnormal electroretinogram or visual evoked potentials. Neuron- ...

*Spatial frequency

2 Visual Acuity, Contrast Sensitivity". University of Utah. Retrieved July 2009. Check date values in: ,access-date= (help). ... How Global Perceptual Context Changes Local Contrast Processing (Ph.D. Dissertation 2003). Updated for Computer Vision ...

*Old age and driving

Do you have low-contrast sensitivity? For example, do you have trouble seeing a gray car at dusk, a black car at night, or a ...

*Visual processing abnormalities in schizophrenia

... and the sensitivity to contrast in sine wave stimuli is characterized by the Contrast sensitivity function. Contrast ... CS1 maint: Multiple names: authors list (link) Slaghuis, W.L. (1998). "Contrast sensitivity for stationary and drifting spatial ... CS1 maint: Multiple names: authors list (link) Skottun, B. C., & Skoyles, J. R. (2007). "Contrast sensitivity and magnocellular ... CS1 maint: Multiple names: authors list (link) Slaghuis, Walter L. (2004). "Spatio-temporal luminance contrast sensitivity and ...

*Left-brain interpreter

This contrasted with the left hemisphere's lower level of sensitivity to variations.[4] ... The fMRI responses from the blocks are then compared.[12] In fMRI studies by Koutstaal the level of sensitivity of the right ... These studies illustrate the role of the left prefrontal cortex in exerting control over one's environment in contrast to the ...

*Photopic vision

Most older adults lose photopic spatial contrast sensitivity. Adults in their 70s require about three times more contrast to ... "Aging and Neural Spatial Contrast Sensitivity: Photopic Vision". Vision Research. 33 (7): 939-949. doi:10.1016/0042-6989(93) ... Their sensitivity ranges overlap to provide vision throughout the visible spectrum. The maximum efficiency is 683 lm/W at a ... Contrast (vision) Cone cell Pelz, J. (1993). Leslie D. Stroebel, Richard D. Zakia, ed. The Focal Encyclopedia of Photography ( ...

*Kitten

ISBN 978-0-226-14576-1. Tootle, John; Friedlander, Michael (1989). Postnatal Development of the Spatial Contrast Sensitivity of ...

*The House of the Dead (novel)

It was a stark contrast with his own heightened sensitivity. During this time in prison he began experiencing the epileptic ...

*Difference of Gaussians

C. Enroth-Cugell; J. G. Robson (1966). "The Contrast Sensitivity of Retinal Ganglion Cells of the Cat". Journal of Physiology. ... A major drawback to application of the algorithm is an inherent reduction in overall image contrast produced by the operation. ... Marr and Hildreth recommend the ratio of 1.6 because of design considerations balancing bandwidth and sensitivity. Note also ...

*Russell L. De Valois

Spatial luminance contrast sensitivity tests of macaque and human observers. Vision Res. 14: 75-81 (1974). Thorell, L.G., De ... Spatial luminance contrast sensitivity tests of macaque and human observers. Vision Res. 14: 75-81 (1974) De Valois, R.L. & ... That the wavelength discrimination and luminance contrast sensitivity measured in monkeys were very similar to those obtained ... had proposed that the percept of color emerged from spectrally-opponent mechanisms in the visual system that contrasted red vs ...

*Sandra Trehub

SE Trehub (July 1973). "Infants' sensitivity to vowel and tonal contrasts". Developmental Psychology. American Psychological ... SE Trehub & Laurel Trainor (May 1992). "A comparison of infants' and adults' sensitivity to Western musical structure". Journal ... SE Trehub (June 1, 1976). "The discrimination of foreign speech contrasts by infants and adults". Child Development. University ... SE Trehub; Dale Bull; Bruce A. Schneider (February 29, 1980). "High-frequency sensitivity in infants". Science. American ...

*Nyctalopia

... may rarely cause a reduction in best night-time acuity due to the impairment of contrast sensitivity function (CSF) which is ... "Laser in situ keratomileusis for myopia and the contrast sensitivity function". Journal of cataract and refractive surgery. 30 ... Contrast vision may also be greatly reduced. Rods contain a receptor-protein called rhodopsin. When light falls on rhodopsin, ...

*Parasol cell

Recordings of S potentials at the axon terminals of RGCs in the LGN suggest that there is high contrast sensitivity in the ... opposed by low contrast sensitivity in cells found in the parvocellular layer. Both old and new world primates have been used ... Due to this contrast information, these cells are good at detecting changes in luminance, and thus provide useful information ... Parasol ganglion cells have high light/dark contrast detection, and are more sensitive at low spatial frequencies than high ...

*Positive and negative predictive values

In contrast, the sensitivity and specificity can be estimated from case-control studies. Suppose the fecal occult blood (FOB) ... The PPV can also be computed from sensitivity, specificity, and prevalence: PPV = sensitivity × prevalence sensitivity × ... Binary classification Sensitivity and specificity False discovery rate Relevance (information retrieval) Receiver-operator ... The NPV can also be computed from sensitivity, specificity, and prevalence: NPV = specificity × ( 1 − prevalence ) ( 1 − ...

*Davida Teller

doi:10.1016/0042-6989(74)90236-3. Daw, N. W.; Enoch, J. M. (1973). "Contrast sensitivity, westheimer function and stiles- ...

*Adele Diamond

Diamond, A. & Herzberg, C. (1996). Impaired sensitivity to visual contrast in children treated early and continuously for PKU. ...

*Infant visual development

Banks, M. S.; Salapatek, P. (1978). "Acuity and contrast sensitivity in 1-, 2-, and 3-month-old human infants". Investigative ... In contrast, healthy adults due to their interaction with people on a frequent basis have fine tuned their sensitivity to ... color sensitivity improves with age. It is generally accepted across all current research that infants prefer high contrast and ... Color sensitivity improves steadily over the first year of life for humans due to strengthening of the cones of the eyes. Like ...

*Positron emission tomography

... and detector-sensitivity correction (for both inherent detector sensitivity and changes in sensitivity due to angle of ... Three different PET contrast agents have been developed to image bacterial infections in vivo: [18F]maltose,[19] [18F] ... 3D techniques have better sensitivity (because more coincidences are detected and used) and therefore less noise, but are more ... PET/CT-System with 16-slice CT; the ceiling mounted device is an injection pump for CT contrast agent ...
We found rhythmic oscillations in visual contrast sensitivity time locked to the execution of a voluntary reaching action. Three aspects appear particularly relevant. First, the oscillations emerge a long time before the action onset. Second, the action was not visually guided, all visual information being completely irrelevant for motor planning and execution. Third, oscillations were found for targets presented in both the left and right visual hemifields. The present results strongly suggest an automatic nonspecific coupling between early motor planning and early visual processing, possibly mediated by transient synchronization of motor and visual neuronal activities.. The observed rhythmicity in visual contrast sensitivity is the likely behavioral signature of oscillatory activity in visual areas within the theta band. Previous studies have established a firm relationship between the probability of perceiving a near-threshold visual stimulus and the prestimulus phase of ongoing cortical ...
Objectives: To determine whether blurred vision caused by exposure to triethylamine (TEA) can be detected by the measurement of contrast sensitivity. Methods: 41 cold box core makers of three foundries and 82 control workers were examined. A detailed ocular and medical history was obtained from the subjects. The contrast sensitivity of the core makers was measured on Monday and Friday of the same week both before and immediately after work and also on a third day, when air samples of TEA were collected. Contrast sensitivity and visual acuity were measured by optotype figures at full contrast, 2.5% contrast, and 0.6% contrast. The changes in contrast sensitivity were used for the analysis. The results of binocular vision and the results of the dominant eye were analysed. Urine specimens for the analysis of TEA were collected on every occasion when contrast sensitivity was measured. Results: 78% of the core makers had had symptoms of blurred vision, and31% had had trouble driving or working. The ...
Purpose: : To evaluate human achromatic spatial contrast sensitivity (CSF) with transient visual evoked cortical potential (tVECP). To compare electrophysiological and psychophysical measurements. Methods: : Six healthy subjects (21 ± 2 years-old) were monocularly tested. The stimuli were black and white horizontal sinusoidal gratings, 40 cd/m2 mean luminance, presented in a 5º circular patch. Six spatial frequencies were used: 0.4, 0.8, 2, 4, 8, and 10 cycles per degree (cpd), in 1 Hz squarewave reversal mode. Electrophysiological contrast thresholds were estimated by linear regressions fitted to data point representing P100 tVECP amplitude as a function of log contrast, extrapolated to zero amplitude. Psychophysics measurements were performed in the same spatial frequencies plus 1 and 6 cpd, using identical spatio-temporal configuration as used in tVECP experiments (dynamic presentation) and using stationary stimuli (static presentation). Psychophysical contrast sensitivity was obtained ...
Contrast sensitivity function is decreased in many disease entities notably: cataract, age related macular degeneration and glaucoma. It is also lowered in individuals that undergo kerato-refractive surgery procedures. Traditional contrast sensitivity tests printed on charts are limited in the fact that a certain working distance is needed and are prone to degradation due to use. The electronic M&S Smart System contrast sensitivity testing unit provides the flexibility to use at variable distance and provides better resolution capabilities especially at lower contrast due to the visual display system. The purpose of the study was to evaluate the short-term repeatability and use of Landolt C contrast sensitivity function test in ocular healthy and in individuals with decreased visual function.. ...
Contrast discrimination is an important type of information for establishing image quality metrics based on human vision. We used a dual-masking paradigm to study how contrast discrimination can be influenced by the presence of adjacent stimuli. In a dual masking paradigm, the observers task is to detect a target superimposed on a pedestal in the presence of flankers. The flankers (1) reduce the target threshold at zero pedestal contrast; (2) reduce the size of pedestal facilitation at low pedestal contrasts; and (3) shift the TvC (Target threshold vs. pedestal contrast) function horizontally to the left on a log-log plot at high pedestal contrasts. The horizontal shift at high pedestal contrasts suggests that the flanker effect is a multiplicative factor that cannot be explained by previous models of contrast discrimination. We extended a divisive inhibition model of contrast discrimination by implementing the flanker effect as a multiplicative sensitivity modulation factor that account for ...
The observed shift in the contrast gain function is consistent with previous measures of spatial vision loss with age. For instance, Sloane, Owsley, and Jackson (1988) measured contrast sensitivity for young and old observers with spatial frequencies ranging from 0.5 to 8 c/deg and luminance levels ranging from mesopic to photopic. At a low temporal frequency, the slope of the sensitivity function (inverse of the threshold function) spanning the range of luminance was steeper for older than younger observers at spatial frequencies below 4 c/deg. This means that older observers required more contrast at low luminance levels to detect a sine-wave grating than their younger counterparts. This pattern of contrast sensitivity loss is consistent with a reduction in the contrast gain slope of the underlying mechanism at low spatial frequencies. In addition, suprathreshold measures of spatial vision performance also support a reduction in contrast gain within one (or both) of the pathways. Losses in ...
This study aimed to explore the neural development status of the visual system of children (around 8 years old) using contrast sensitivity. We achieved this by eliminating the influence of higher order aberrations (HOAs) with adaptive optics correction. We measured HOAs, modulation transfer functions (MTFs) and contrast sensitivity functions (CSFs) of six children and five adults with both corrected and uncorrected HOAs. We found that when HOAs were corrected, children and adults both showed improvements in MTF and CSF. However, the CSF of children was still lower than the adult level, indicating the difference in contrast sensitivity between groups cannot be explained by differences in optical factors. Further study showed that the difference between the groups also could not be explained by differences in non-visual factors. With these results we concluded that the neural systems underlying vision in children of around 8 years old are still immature in contrast sensitivity.
Human contrast sensitivity to visual patterns vs. model predictions.a, Probability distribution of the 512 possible 3×3 1-bit pixel patterns (grey histogram).
A two-interval forced choice (2-IFC) task was used to measure disparity threshold. Each trial began with a fixation image (Figure 3a), consisting of a dark fixation dot (diameter of 6.25 min) in the center of a random-dot background (Michelson contrast = 0.2). The vertical and horizontal positions of the two monocular images could be adjusted manually to achieve better convergence in the beginning of each block. After successfully combining the two monocular images into one steady cyclopean image, observers pressed the space bar on the computer keyboard to start the presentation of a 1300-ms dynamic RDS movie. The movie contained two 400-ms stimulus intervals, each consisting of eight frames of independently sampled RDS and delimited by a brief tone in the beginning and a 500-ms interstimulus interval. Dynamic RDS with zero disparity was presented during the 500-ms interstimulus interval. The RDS in one of the randomly chosen intervals contained a horizontal disparity in the lower half of the ...
With the increasing rise of toxicity, and the increasing awareness of this huge problem, we need to have ways of determining which patients are likely to b
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Neural activity during repeated presentations of a sensory stimulus exhibits considerable trial-by-trial variability. Previous studies have reported that trial-by-trial neural variability is reduced (quenched) by the presentation of a stimulus. However, the functional significance and behavioral relevance of variability quenching, and the potential physiological mechanisms that may drive it have rarely been studied. Here we recorded neural activity with EEG as subjects performed a two-interval forced-choice contrast discrimination task. Trial-by-trial neural variability was quenched by approximately 40% after the presentation of the stimulus, relative to the variability apparent before stimulus presentation, yet there were large differences in the magnitude of variability quenching across subjects. Individual magnitudes of quenching predicted individual discrimination capabilities such that subjects who exhibited larger quenching had smaller contrast discrimination thresholds and steeper ...
Near Pelli-Robson Contrast Sensitivity Chart. For use at 16 in (40cm) Includes three charts, each of which is scrambled to avoid memorization.Buy online!
04.02.2019 ► Spatial resolution is a key property of eyes when it comes to understanding how animals perceive visual signals. In the current paper (J. Vision), Matteo Santon et al. describe the contrast sensitivity function of a small, benthic marine triplefin fish, using an optokinetic reflex approach. Compared to other fish, the authors conclude that such reflex seems to be adapted to process low spatial frequency information from stimuli in the peripheral visual field and show that small marine fish can feature excellent contrast sensitivity at optimal spatial frequency. ...
A multiresolution-analysis-based local contrast transform is proposed to enhance local structures in x-ray images. The local contrast is defined as a ratio of the local intensity variation to the local mean. With wavelet multiresolution decomposition, the detail coefficients and approximation coefficients are interpreted, respectively, as local variations and local averages in virtue of the localization property of wavelet transform. Based on the local contrast transform, an algorithm is developed to modify coefficients before wavelet synthesis. An across-scale local contrast is obtained when the scale associated with the local variation is different from that of the local mean. The nonlinearity and local adaptiveness properties of local contrast transform result in structural enhancement in local dark regions in the reconstructed images. We applied this technique to deboned poultry inspection using x-ray images. Because of its high x-ray absorption, a foreign inclusion appears as a ...
Can anybody suggest some colors and simple fonts fot text (heading) on a grey background. Please check the image attached. Thank you!
Nodes with grey background indicate a prediction accuracy for the nodes greater than 0.6. Isolated nodes do not have connections due to the structure difference
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We assessed the accuracy of contrast-defined shape detection of stimuli of constant aspect ratio, namely, circular bandpass stimuli whose radii were sinusoidally varied about a mean radius. Performance for these contrast-defined shapes, which we show is determined by the global rather than the local attributes of the stimulus, is 2-8 times worse than that for their luminance-defined counterparts, suggesting separate processing limitations. By spatially and orientationally filtering the two-dimensional fractal-noise carriers of which these stimuli were composed, we determined whether there are specific rules concerning the spatial and orientational input to shape detectors from mechanisms sensitive to the carrier structure. The results suggest that second-order circularity detectors receive mixed input from spatial-frequency-tuned and orientationally tuned cells.. © 2001 Optical Society of America. Full Article , PDF Article ...
Principal Investigator:KAJITA Etsuko, Project Period (FY):1997 - 1998, Research Category:Grant-in-Aid for Scientific Research (C), Section:一般, Research Field:Nursing
Dynamic Vision Sensors (DVS) have recently appeared as a new paradigm for vision sensing and processing. They feature unique characteristics such as contra
The CyberPower Smart App Sinewave PR1000LCD uninterruptible power supply (UPS) with LCD Control Panel and Active PFC compatible pure sine wave output safeguards mission-critical servers, telecom equip
Researchers have developed an easy-to-build camera that produces 3D images from a single 2D image without any lenses. In an initial application of the technology, the researchers plan to use the new camera, which they call DiffuserCam, to watch microscopic neuron activity in living mice without a microscope. Ultimately, it could prove useful for a wide range of applications involving 3D capture.
OSAs Annual Enabled by Optics Contest provides companies and students with a platform to explain how optics technology has impacted our world.
Lab Manager features articles relating to management, technology, and equipment common to laboratories in industry, medicine, universities, and
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b. Dark-adapted static threshold perimetric profiles along the horizontal meridian for the central 60 degrees. For the normal, the lines delimit +/- 2 standard deviations from the mean normal using the 500 nm stimulus (rod-mediated detection, upper set) and a 650 nm stimulus at the cone plateau (cone-mediated detection, lower set). For the patient profiles, the curves describe the responses to the two different stimulus wavelengths used. Letters above the sensitivity measurements in the patient are the photoreceptor mediations for detection of the 500 and 650 nm stimuli: C = cone detection. N = nasal; T = temporal. ...
Feel free to contact Royce Specialty Steel to learn more about how our stock and custom perforated metal product offerings can benefit your industrial operation, and please let us know about any specific customization requirements or special requests. Well also be happy to provide a no-obligation quote and help with your ordering process. If you need assistance calculating the open area, contact one of our friendly representative and wed be happy to assist you.. ...
Three color reductive linoleum blockprint on 11x15 Stonehenge paper. Printed on a Universal 1 Vandercook proofing press. Signed, limited edition of 30. Indicate blue background or grey background in order. Extra shipping costs on framed print only.
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Meaning and definition of the name Gabor. Learn the meaning of Gabor, learn about the origin of the name Gabor and find other information about the name Gabor.
|i|Spatial Vision|/i| is continued as |i|Seeing and Perceiving|/i|. See |a href=http://www.brill.com/sp target=_blank|www.brill.com/sp|/a| for more information.
The luminance values in cd/m2 are not very reliable, since camera sensitivities can easily differ up to 50% from their nominal value. Typically, the real luminance is 30% lower than this number. The area used for calculation is chosen such that it corresponds to a viewing angle of ±14° horizontally and ±10.5° vertically, which is equivalent to viewing the screen from a distance of about 1.5 times the diagonal size. Unfortunately, there is a lot of variation in how cameras use EXIF settings. If photos from your camera your produce unusable results, try coming back in a few days. I review submitted pictures regularly and try to fix problems.. ...
Hi, Im thinking of buying an i3-4130 based HTPC. I have an i5 desktop with integrated graphics HD-4000 which has an Adaptive Contrast option. Does
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The goal of this study was to predict visual acuity (VA) and contrast sensitivity function (CSF)with tissue redness grading after pterygium surgery. A total of 67 primary pterygium participants were selected from patients who visited an ophthalmology clinic. We developed a semi-automated computer program to measure the pterygium fibrovascular redness from digital pterygium images. The final outcome of this software is a continuous scale grading of 1 (minimum redness) to 3 (maximum redness). The region of interest (ROI)was selected manually using the software. Reliability was determined by repeat grading of all 67 images, and its association with CSF and VA was examined. The mean and standard deviation of redness of the pterygium fibrovascular images was 1.88 ± 0.55. Intra-grader and inter-grader reliability estimates were high with intraclass correlation ranging from 0.97 to 0.98. The new grading was positively associated with CSF (p , 0.01) and VA (p , 0.01). The redness grading was able to ...
Far contrast sensitivity (ie, the ability to detect slight changes in luminance before they become indistinguishable) was assessed binocularly with the participants best spectacle correction at a distance of 3 m using the Vector Vision CSV 1000 illuminated box (one site) and the Vision Contrast Test System (other site). Contrast sensitivity was assessed at spatial frequencies of 1.5, 3, 6, 12, and 18 cycles per degree (cpd). For CSV 1000, contrast sensitivity was not measured at spatial frequency 1.5 cpd because there was no option for this frequency. Raw scores were transformed to logMar (logarithm of the minimum angle of resolution) units. A higher numeric value represents better contrast sensitivity ...
PubMed Central Canada (PMC Canada) provides free access to a stable and permanent online digital archive of full-text, peer-reviewed health and life sciences research publications. It builds on PubMed Central (PMC), the U.S. National Institutes of Health (NIH) free digital archive of biomedical and life sciences journal literature and is a member of the broader PMC International (PMCI) network of e-repositories.
The CSF represents the reciprocal of the minimum contrast required to detect sinusoidal gratings that vary in spatial frequency (the number of cycles per degree of visual angle, cpd). As shown in the top panel of figure 3, scotopic CSFs were found to be low pass for all age groups. Statistically significant age related declines in contrast sensitivities were found for spatial frequencies at or below 1.2 cpd. This greater loss in contrast sensitivity at low spatial frequencies is quite different from photopic contrast sensitivity changes with age in which the decline in sensitivity is only at higher spatial frequencies for luminance varying stimuli.26,27 An analysis of these results in terms of optical factors could be rejected, while the results are consistent with age related changes in scotopic neural pathways.. The bottom panel of figure 3 shows the highest spatial frequency (the CSF "cut-off" frequency) that can be detected under scotopic conditions as a function of age. The axis on the ...
Laser in situ keratomileusis (LASIK) surgery has been performed worldwide since 1990. Historically, LASIK has been reported to decrease contrast sensitivity post operatively and patients have been advised to take the day off of work and potentially the day after LASIK. More recently, utilizing advanced laser technology for optimized corneal ablation and creation of the flap has the potential for improved LASIK surgery results and improved recovery time. Visual recovery and management of immediate post operative visual acuity is important for patient satisfaction ...
A new contrast sensitivity system was built with an iPAD connected to a 24" TFT-screen TFT monitor with a HDMI cable. The monitor was calibrated with a colorimeter. An image, showing incrementing spatial frequency along the x-axis and decreasing contrast along the Y-axis, was generated with custom software that allowed imaging on the the iPAD or the TFT monitor. While watching the image on the TFT monitor at 5 m, the subject was asked to draw a line in between contrast perceived and no contrast perceived. The line drawn by the subject was shown on the screen in use after the end of the tracking. The contrast perceived at each spatial frequency was stored in a data file. Totally, 20 subjects with visual acuity 1.0 and no known eye pathology were randomized on 2 groups with 6 males and 4 males to be measured for contrast sensitivity on both eyes with Vistech 6500 chart or UCST, depending on group belonging. Spectral contrast sensitivity was recorded for each eye and the time consumed for ...
PURPOSE: Loss of neuroretinal structure and function, ascribed to a HIV-associated Neuroretinal Disorder (HIV-NRD), in the absence of ocular opportunistic infections, has been reported in HIV-infected individuals treated with combination antiretroviral therapy (cART). Whether HIV-infected individuals with prolonged well-suppressed infection remain at risk for HIV-NRD, is unknown. METHODS: Ninety-two HIV-infected men with suppressed viremia on cART for at least 12 months (HIV+) and 63 HIV-uninfected, highly comparable, male controls (HIV-), aged at least 45 years, underwent functional measurements of spatial (Pelli Robson contrast sensitivity [PR CS]) and temporal contrast sensitivity (TCS) and straylight, as well as spectral-domain optical coherence tomography analysis measured total and individual retinal layer thickness ...
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Background: Amblyopic observers present abnormal spatial interactions between a low-contrast sinusoidal target and high-contrast collinear flankers. It has been demonstrated that perceptual learning (PL) can modulate these low-level lateral interacti
Ive heard about this a while ago, but now its statistically proven. Shooting Games can increase/help a players vision. It has to do with Contrast Sensitivity, apparently shooting games (Like Call of Duty 4 or Halo 3) increase and exercise your Contrast Sensitivity. What is contrast sensitivity? It is your ability to notice tiny changes…
We present a spatial frequency domain multiplexing method for extending the imaging depth range of a SDOCT system without any expensive device. This method uses two reference arms with different round-trip optical delay to probe different depth regions within the sample. Two galvo scanners with different pivot-offset distances in the reference arms are used for spatial frequency modulation and multiplexing. While simultaneously driving the galvo scanners in the reference arms and the sample arm, the spatial spectrum of the acquired two-dimensional OCT spectral interferogram corresponding to the shallow and deep depth of the sample will be shifted to the different frequency bands in the spatial frequency domain. After data filtering, image reconstruction and fusion the spatial frequency multiplexing SDOCT system can provide an approximately 1.9 fold increase in the effective ranging depth compared with that of a conventional single-reference-arm full-range SDOCT system ...
Disclosed herein are systems and methods for calibrating a continuous analyte sensor, such as a continuous glucose sensor. One such system utilizes one or more electrodes to measure an additional analyte. Such measurements may provide a baseline or sensitivity measurement for use in calibrating the sensor. Furthermore, baseline and/or sensitivity measurements may be used to trigger events such as digital filtering of data or suspending display of data.
Mean age of LCG (48 eyes) was significantly higher(29.26±5.00vs26.45±3.74,P=0.006). F/M ratio was comparable in two groups and 2.7 in total. Post-op CDVA was comparable in two groups(1.22±0.23vs1.25±0.44,P = 0.7). Post-op UDVA was higher in HCG(1.31±0.37vs1.15±0.23,P =0.001). Pre-op mean manifest SE was more myopic in LCG(-4.41±2.02vs-3.28±1.41,P = 0.001) while post-op SE were comparable. Mean post-op photopic and mesopic contrast sensitivities were better in HCG; however mean improvement of contrast sensitivities were higher in LCG. Pre-op mean Defocus and Pentafoil aberrations were higher in LCG. After the operation they became comparable ...
Small changes in contrast sensitivity after LASIK can be documented using a dedicated computer program displaying optotypes on a monitor. Contrast sensitivity is impaired at 1 and 3 months, while complete recovery is observed after 6 months. This course is partly concealed if the spectacle refraction is not taken into account ...
A red background is used for men whose data has not yet been fully analyzed. His position on the tree is not yet final, and will in general be downstream of the current position. He may not be positive for all the SNPs/INDELs in the block he descends from.. Men whose NGS data have been fully analyzed are indicated with a grey background color.. Those men with a grey background and a pink bar to their left have been finalized, but havent gone through as much scrutinity as earlier kits have. In particular, no search has been made for recurrent SNPs or other unusual mutations. For the vast majority of kits, this has no effect at all, but I will review them as necessary in the future.. ...
A red background is used for men whose data has not yet been fully analyzed. His position on the tree is not yet final, and will in general be downstream of the current position. He may not be positive for all the SNPs/INDELs in the block he descends from.. Men whose NGS data have been fully analyzed are indicated with a grey background color.. Those men with a grey background and a pink bar to their left have been finalized, but havent gone through as much scrutinity as earlier kits have. In particular, no search has been made for recurrent SNPs or other unusual mutations. For the vast majority of kits, this has no effect at all, but I will review them as necessary in the future.. ...
We know that adults contrast sensitivity and spatial resolution are better along the horizontal than vertical meridian -a.k.a. horizontal vertical anisotropy (HVA)- and better in the lower than upper vertical meridian -a.k.a. vertical meridian asymmetry (VMA; Carrasco et al., Spatial Vision 2000, JOV 2002). We also know that for adults the speed of information accrual follows the same pattern, i.e. it is faster along the horizontal meridian and slowest at the North locations (Carrasco et al., VSS 2002). In this study, we investigated the developmental course of these asymmetries with children ages 5-12, by using stimuli of different levels of familiarity, such as shapes, letters and numbers. We used a 4AFC character identification task to determine the presence and extent of the HVA and VMA. Each trial consisted of a central fixation point followed by a 1 stimulus, presented for 50 ms. The stimulus appeared at one of 10 possible eccentricities, ranging from 4 to 13 , along each of the 8 ...
An apparatus is disclosed for making unchirped holographic diffraction gratings that are formed from curved lines in a thin film. The gratings so made focus as well as reflect light that is confined to the film incorporating the grating. SU BACKGROUND OF THE INVENTION Gratings have been incorporated in integrated optics devices for several purposes, including the fabrication of distributed feedback lasers, light-wave couplers, and band-rejection filters. Integrated-optics gratings known to the prior art were composed at straight lines, and therefore could not focus the light being processed. Gratings that combine focusing and diffraction were known to be desirable, but the prior art was unable to produce them. The closest prior art that has come to our attention is a method and apparatus for producing curved-line holographic gratings that have unequally spaced, or chirped, lines (U.S. Pat. No. 3,578,845, issued on May 18, 1971 to K. E. Brooks et al). This reference teaches the production of gratings
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1. The difference in density/IR exposure between two adjacent areas on an image. One of the two properties that allow detail to be visualized on an image. 2. How do low contrast images differ from high contrast images? 2. Low contrast images have many shades of gray (more information on the image). Also referred to…
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This article is full of error. Ive a Ph.D in vision and have been a consultant for one of the top TV companies. The notion that people can resolve 60 pixels per degree is dead wrong, as others have said. What matters is resolution acuity, not maximum resolvable angle. Humans can resolve 60 cycles/degree *under optimal conditions*. Each cycle is pair of on/off pixels. Think of a vertical line stripes, one pixel, one white one black. A 4K set has 2000 cycles. At 60 cycles/degree, that means that the resolution limit is achieved when the image is 2000/60=33.3 degrees wide. For a 55 inch diagonal (which is 48 inches or 4 feet wide), that limit is at about 6 feet. Thats because visual angle figures at (2*arctan(4 feet/(2*6 feet))=33.39. Sit further away and any benefit of 4K is lost. This is straight visual physiology and not a debatable point, despite what the many misinformed commentaries on the interest try to claim.. HOWEVER. The acuity limit is 60 cycle/degrees only under optimal conditions. ...
L: First cycle degree/Bachelor. Qualification required: High School Diploma, duration 3 years.. LM: Second cycle degree/Two year Master. Qualification required: First cycle degree, duration 2 years.. LMCU: Single cycle degree/Combined Bachelor and Master. Qualification required: High School Diploma, duration 5/6 years.. TDM: The programme or one of its curricula lead to a dual or multiple degree.. TC: The programme leads to a joint degree.. EN: The programme or one of its curricula are delivered in English. ...
A 4-year study following trifocal IOL implantation (AT LISA tri 839MP, Carl Zeiss Meditec) found that the lens provided good distance, near, and intermediate visual acuity. The lens also improved patient quality of vision with better diffraction and less reduction in contrast sensitivity. ...
A screen shot of the variant output. The top half of the box is a representation of the grid from the ACMG/AMP guidelines with each rule that has been activated for this variant shown in colour. Boxes with a grey background represent rules that cannot be computationally predicted and that require user input. This grid is fully interactive - click on a box to add or remove it as evidence.. The bottom half of the box displays the evidence that went in to assessing each of the ACMG/AMP rules, including case and control frequencies and links out to various external resources (PubMed, Google, ClinVar, UCSC, ACGV, ExAC and the Beacon Network).. To complete the classification of your variant(s), follow the links out to publications and ClinVar to find any reported clinical or functional information. Use this, along with any information you have about your specific patient/sample, to activate any rules that have not been activated automatically, by simply clicking on the rule you want to activate. When ...
Reply Rachael January 16, 2014 at 3:03 pm I like the overall cleaner feel of this reader mode, but I have a few problems with it that are fairly significant.. There is way too much bright, white space. It was hurting my eyes. The main text is more than double-spaced with max width of 600px and massive padding so theres empty white space on each side and anything over three or four lines of text takes up multiple pages with huge gaps between each line. I am able to fix this on my main computers by fiddling with the CSS via a Grease Monkey script, but that does nothing for me on other computers.. The left sidebar is too faint of text on that grey background. I could fiddle with that as well, but it is an annoyance not actually giving me headaches like the other so I havent bothered yet. I have nothing in the other sidebar (Livebar) so I dont care about it at the moment.. The old reader moved items up as I clicked "N" to move to the next entry so whatever was the focus was at the top. It no ...
Whenever the Magical changes position and every time the time changes (so once every minute), a strange grey background appears behind the text of the magical. To fix it, you have to click and un-click the "bold" option for the offending section. Please fix this. It looks odd. photo here: http://img684.imageshack.us/f/snapndrag208.jpg/. Submitted at 01:20am on 04 Apr 2011 ...
Estimation, lag selection, diagnostic testing, forecasting, causality analysis, forecast error variance decomposition and impulse response functions of VAR models and estimation of SVAR and SVEC models.. ...
Most projectors claim to have a very high contrast ratio along the lines of 10,000:1 - 15,000:1 reach this number with an adjustable iris. The aperture changes...
In this paper, we theoretically and experimentally demonstrated the residual chromatic dispersion (CD) monitoring of 100-Gbit/s carrier suppress return-to-zero differential quadrature phase shift keying (CS-RZ DQPSK) signals by evaluating the asymmetry ratio of delay tap asynchronous sampling. This scheme can easily differentiate the positive and negative residual CD of the fiber link. The resolution of this scheme is better than 8ps/nm and the measurable range is around ± 24ps/nm for 100Gbit/s CS-RZ DQPSK signals. We can also simultaneously realize both signed CD monitoring and demodulation of CS-RZ DQPSK signal based on only one demodulator. © 2010 Optical Society of America ...
F. L. Kien, K. Vogel and W. P. Schleich, "Arc field states, photon statistics probes and quantum lenses: field evolution and atomic motion in a dispersive interaction model" , Quantum and Semiclassical Optics: Journal of the European Optical Society Part B , vol. 9 , no. 1 , pp. 69--101 , 1997. {IOP} Publishing ...
Dr. Robert R. Alfano, a pioneer in ultrafast optical science and engineering, is the 2016 recipient of the Optical Society of America (OSA) Michael S.
Today I had my first ultrasound. Im not sure, but Im very scared that I will receive bad news soon. Today I actually didnt get the clear answer. The doctor saw an embryo but she wasnt able to see the development inside the emryo. (Im sorry because of my English, it is not my native language)The doctor also wasnt 100% sure that the embryo is empty, while as she said, they just got a new ultrasound equipment and the black and white contrast are maybe not fixed yet properly. Anyway, she said that the embryo is 4 weeks old (the pregnancy calculator gives another result), but she is not sure about the development inside the embryo ...
Hallo @ll I wanna include High Contrast´s chances in my set, but dislike to use LP on stage! Do you know anything about a EP release, whitelable...
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To understand the more complex aspects of frequency and phase encoding of the MR image, it is necessary to review what happens when two sine waves are added together. If two sine waves have the same frequency but different phases, their summation is another sine wave with the same base frequency but a different amplitude and phase. When the two waves are perfectly in phase with each other, their signals augment each other. When they are slightly out of phase with each other, the overall signal is diminished, and they are said to destructively interfere. When the phase shift between them reaches 180°, the two waves exactly cancel each other ...
Also, I think maybe slight differences in the way the brightnesses of different hues are perceived could lead to them balancing the brightness in such a way that they see all of the brightnesses as all the same, but some people would not and might find it more aesthetically pleasing to order by brightness and rack up a few points that way. Maybe? Because I had to consciously ignore brightness in a few places because it looked like it was going from darker, to lighter, to darker again within a few squares going by the right order on hue ...
Four experiments are reported in which the subjects had to respond to a target that masked a preceding prime via metacontrast masking. In one part of Experiment l, the subjects discriminated the...
I did some global sharpening and Local Contrast Enhance (just the birds) on these. I never trust my screen or eyes to pick up on halos. I think I see
9781472912770 Our cheapest price for The Brightness of Things An Adventure in Light and Time is not available. Free shipping on all orders over $35.00.
Hands folded to make a shadow rabbit. Didnt know what to do for background, so I will let it be as it is now. Edit: Made some more contrast on the thumbnail, and changed the shadow to be a little bigger. (I think it looks more realistic that way) I also made the background darker.
The 5PB1214 is a high-performance TCXO / LVCMOS clock fanout buffer with individual OE pin for each output. The CLKIN pin can accept either a square wave (LVCMOS) or clipped sine wave (such as TCXO clipped sine wave output) as input ...
Ciao a tutti, non so tradurre correttamente OVER-IT, come caratteristica (glare=luce) di questa attrice TV che interpreta il ruolo di donna oltre i 40...
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(Family Features) Its a common scenario: no time for breakfast, so youre snacking on something sweet in the break room at 9 a.m. Two hours later you hit the
Its easy to divide a sine wave (curve) into any number of slices so that area of all slices become equal. Its a problem of definite integral. Area...
Monochromators with optical gratings for spectral dispersion are every day tools in spectroscopy from UV to IR. The common Czerny-Turner set up has been ...
Glare Sensitivity is a debilitating loss of visual acuity in bright lighting, such as when near a bright light source or outdoors in bright sunlight. Patients suffering from glare sensitivity will be unable to see the separate contours of brightly lit objects, and their surroundings may merge into a "wall" of bright white. Glare sensitivity may be a symptom of certain eye conditions or could be a temporary side effect from some eye procedures and surgeries.. Glare sensitivity can be a symptom of:. ...
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J. Allman, F. Miezin, & E. McGuinness (1985). Stimulus specific responses from beyond the classical receptive field: neurophysiological mechanisms for local-global comparisons in visual neurons. Annual Review of Neuroscience 8:407-430. N. Bruce & J. K. Tsotsos (2006). Saliency Based on Information Maximization. In: Advances in Neural Information Processing Systems, 18:155-162. M. W. Cannon & S. C. Fullenkamp (1991). Spatial interactions in apparent contrast: inhibitory effects among grating patterns of different spatial frequencies, spatial positions and orientations. Vision Research 31:1985-1998. R. Carmi & L. Itti (2006). Visual Causes versus Correlates of Attentional Selection in Dynamic Scenes. Vision Research 46(26):4333-4345. F. Crick (1984). Function of the thalamic reticular complex: the searchlight hypothesis. Proceedings of the National Academies of Sciences USA 81(14):4586-90. R. Desimone & J. Duncan (1995). Neural mechanisms of selective visual attention. Annual Review of ...
Short presentation of a large moving pattern elicits an Ocular Following Response (OFR) that exhibits many of the properties attributed to low-level motion processing such as spatial and temporal integration, contrast gain control and divisive interaction between competing motions. Similar mechanisms have been demonstrated in V1 cortical activity in response to center-surround gratings patterns measured with real-time optical imaging in awake monkeys. More recent experiments of OFR have used disk gratings and bipartite stimuli which are optimized to study the dynamics of center-surround integration. We quantified two main characteristics of the global spatial integration of motion from an intermediate map of possible local translation velocities: (i) a finite optimal stimulus size for driving OFR, surrounded by an antagonistic modulation and (ii) a direction selective suppressive effect of the surround on the contrast gain control of the central stimuli [Barthelemy06,Barthelemy07].In fact, the ...
PURPOSE To research the mechanism of neurophysiological treatment of amblyopia by observing the visual cortex activation under rotating grating stimulus with functional magnetic resonance imaging (MRI), and identify the components of the activation. METHODS Nine healthy volunteers were examined using gradient-recalled echo and echo-planar imaging (GRE-EPI) pulse sequence performed at the 1.5 Tesla MRI scanner. In the block designing, rotating grating, stationary grating and luminance were plotted as task states, stationary grating, luminance and darkness as control states, respectively. The tasks of stimuli included 6 steps. Imaging processing and statistical analysis were carried out off-line using statistical parametric mapping (SPM99) software in single-subject. RESULTS Some individual areas of visual cortex were activated by various stimuli information supplied by rotating grating. The strong activation in the middle of occipital lobe related to the stimuli of luminance, bilateral activation of
Conclusion: SLCLA at 2.5% and 1.25% contrast levels correlates with retinal morphology and P100 latency and predicts some aspects of vision-related QoL in MS. More importantly, using a prospective cross-sectional approach we provide evidence that extending the MSFC by SLCLA as an additional visual component increases the performance of MSFC to capture MS-related disability. Longitudinal data on the relation between SLCLA, MSFC, and QoL will be available in the near future. (Source: BMC Neurology)
p,Type 1 cannabinoid receptors (CB1Rs) are widely expressed in the vertebrate retina, but the role of endocannabinoids in vision is not fully understood. Here, we identified a novel mechanism underlying a CB1R-mediated increase in retinal ganglion cell (RGC) intrinsic excitability acting through AMPK-dependent inhibition of NKCC1 activity. Clomeleon imaging and patch clamp recordings revealed that inhibition of NKCC1 downstream of CB1R activation reduces intracellular Cl(-) levels in RGCs, hyperpolarizing the resting membrane potential. We confirmed that such hyperpolarization enhances RGC action potential firing in response to subsequent depolarization, consistent with the increased intrinsic excitability of RGCs observed with CB1R activation. Using a dot avoidance assay in freely swimming Xenopus tadpoles, we demonstrate that CB1R activation markedly improves visual contrast sensitivity under low-light conditions. These results highlight a role for endocannabinoids in vision and present a ...
Adams, Donald and Stefan Preble. "High-Sensitivity Linear Silicon Electro-Optic Modulation and Filtering for RF Photonics." Proceedings of the Frontiers in Optics. Ed. Optical Society of America. Rochester, NY: n.p., 2012. Web. *. Cao, Liang, et al. "Direct Observation of DC Kerr Electro-Optic Modulation using Silicon Nanocrystals." Proceedings of the Frontiers in Optics. Ed. Optical Society of America. Rochester, NY: n.p., 2012. Web. *. Aboketaf, Abdesalam, Liang Cao, and Stefan Preble. "Robust Phase-Shift-Keying Silicon Photonic Modulator." Proceedings of the Frontiers in Optics. Ed. Optical Society of America. Rochester, NY: n.p., 2012. Web. *. Cao, Liang, Abdelsalam Aboketaf, and Stefan Preble. "Efficient Thermal Control of CMOS Compatible Silicon Photonic Devices using a Micro-Oven." Proceedings of the Frontiers in Optics. Ed. Optical Society of America. Rochester, NY: n.p., 2012. Web. *. Aboketaf, Abdesalam, Liang Cao, and Stefan Preble. "On-Chip OTDM Signal Generator with Minimal Loss." ...
Looking for online definition of achromatic color in the Medical Dictionary? achromatic color explanation free. What is achromatic color? Meaning of achromatic color medical term. What does achromatic color mean?
In the visual system, prolonged exposure to a high contrast stimulus leads to a decrease in neuronal responsiveness, referred to as contrast adaptation. Contrast adaptation has been extensively studied in carnivores and primates, but has so far received little attention in mice. This thesis explores contrast adaptation and its mechanisms in mouse primary visual cortex (V1). Using extracellular tetrode recordings in mouse V1, I found contrast adaptation to be orientation unspecific. While this finding differs from reports in carnivores and primates, it is consistent with the notion that responsiveness of individual neurons is influenced by the activity history of the local network. Adaptation was also found to be cell-type specific, as putative parvalbumin (PV) expressing interneurons underwent less adaptation than other cell types. There is debate whether adaptation arises within the cortex or is inherited from the earlier stages in the visual pathway (e.g. visual thalamus or retina). In order ...
Five forms of perimetry were used, two clinical tests and three custom 31 tests. One form of custom stimulus was a simple luminance increment, known as a blob stimulus, 35 that is defined by the standard deviation of the Gaussian window. The other form of custom stimulus was a Gabor sine, 31 a sine wave grating multiplied by a Gaussian window. Examples of the stimuli used are shown in the left panel of Figure 1. The top row shows, from left to right, size III, 0.25° blob, 0.5° blob, size V, 0.50 cycle/deg Gabor. The size V stimulus was not used in these experiments and is shown for reference. The second row shows the largest blob (1.11°) on the left and a 0.25 cycle/deg Gabor on the right. The third row shows the largest Gabor (0.14 cycle/deg), and the fourth shows the frequency-doubling stimulus (0.5 cycle/deg in a 5° square window). Size III (top left) and frequency-doubling (bottom) stimuli are dramatically different in size: The frequency-doubling stimulus is 5° wide, and the size III ...
The founders of Wasatch Photonics began writing Volume Phase Holographic (VPH) gratings in dichromated gelatin over 40 years ago, and no one does it better. We draw on our multiple patented design technologies to optimize each grating to its application, from stock gratings for R&D to custom gratings for our many OEMs. Our strengths include high efficiency, low polarization sensitivity, and uniform performance over broad bandwidths & large clear apertures - all in a robust, field-tested package. As an experienced volume gratings supplier, we offer quality, performance, and consistency you can count on.. Download the VPH Gratings brochure Our enhanced volume phase gratings are unsurpassed for use in pulse compression, astronomy, and hyperspectral imaging. Our patented Dickson gratings and HD gratings meet the needs for demanding applications in Optical Coherence Tomography (OCT), Raman & fluorescence spectroscopy, and other high speed, low light level applications.. ...
Amblyopia is a neurodevelopmental disorder of the visual system that is caused by abnormal binocular visual experience during early childhood, typically due to anisometropia or strabismus [1]. Amblyopia causes a range of monocular deficits in the affected eye including impaired visual acuity [1], contrast sensitivity [2], motion perception [3, 4] and excessive crowding [5] (see [6] for a recent review). Patients with amblyopia also experience impaired binocular vision. In particular, the fellow eye often suppresses the amblyopic eye when both eyes are open, and stereopsis is commonly impaired or absent [7]. Stronger interocular suppression has been associated with poorer stereopsis and monocular visual acuity in patients [8-11], as well as poorer amblyopic eye contrast sensitivity in animal models of amblyopia [12, 13].. In children, the visual acuity deficit associated with amblyopia can be treated monocularly by optically correcting any significant refractive error and then occluding ...
CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): this article we investigate to what extent the statistical properties of natural images can be used to understand the variation of receptive field properties of simple cells in the mammalian primary visual cortex. The receptive fields of simple cells have been studied extensively (e.g., Hubel & Wiesel 1968, DeValois et al. 1982a, DeAngelis et al. 1993): they are localised in space and time, have band-pass characteristics in the spatial and temporal frequency domains, are oriented, and are often sensitive to the direction of motion of a stimulus. Here we will concentrate on the spatial properties of simple cells. Several hypotheses as to the function of these cells have been proposed. As the cells preferentially respond to oriented edges or lines, they can be viewed as edge or line detectors. Their joint localisation in both the spatial domain and the spatial frequency domain has led to the suggestion that they mimic Gabor
Applications of Holography to Interferometric Testing," Eastman Kodak Report F-013747-KU, 1967.. "Coherence vs Fringe Visibility in Laser Interferometers," Eastman Kodak Report A002003-KU, 1967.. "Improving Brightness of Holographic Images," Eastman Kodak A-002072-MU, 1967.. "Optical Testing by Holographic Interferometry," Eastman Kodak A-002055-MU, 1967.. "A General Purpose Holographic Differential Interferometer." Eastman Kodak, 1968.. "Radiometry & Photometry," American Journal of Physics, Vo1. 36, No. 11, Part 1, November 1968, pp. 977-979.. "Holographic Multiple Pass Interferometer for Plasma Physics," co-authors W.R. McCluney, J. G. Hirschberg,, L. R. Hazelton, and A. Aggarwal, Optical Society of America Annual Meeting, Chicago, IL, 24 October 1969, Journal of the Optical Society of America, Paper FB18, Vol. 59, p. 1541 (1969).. "The HOMIN, A Holographic Multiple Pass Interferometer," co-authors J. G. Hirschberg, W. R. McCluney, A. Aggarawal, and L. R. Hazelton. Univeresity of Miami ...

2011 ACR/ARHP Annual Scientific Meeting: Affiliation Index A2011 ACR/ARHP Annual Scientific Meeting: Affiliation Index A

Sensitivity of the New EULAR/ACR Classification Criteria for Polymyalgia Rheumatica in Comparison with the Former Ones: A ... Non-Invasive MRI by Omitting Intravenous Contrast Injection; Does It Change the Radiologic Assessment of Knee Joint Pathologies ... Sensitivity to Change of the 7-Joint Ultrasound (US7) Score Among Patients with Different Musculoskeletal Diseases Under Twelve ...
more infohttps://acr.confex.com/acr/2011/webprogram/affiliationa.html

Better contrast sensitivity tests needed - American Academy of OphthalmologyBetter contrast sensitivity tests needed - American Academy of Ophthalmology

This article reviews the importance of contrast sensitivity to vision and its role in identifying many ocular diseases, and ... They say that an ideal contrast sensitivity test would evaluate peak contrast sensitivity function, be reliable and not be ... This article reviews the importance of contrast sensitivity to vision and its role in identifying many ocular diseases, and ... The authors conclude that it is important for a contrast sensitivity testing method to have strong reliability to differentiate ...
more infohttps://www.aao.org/editors-choice/better-contrast-sensitivity-tests-needed

Contrast Sensitivity Testing - AllAboutVision.comContrast Sensitivity Testing - AllAboutVision.com

Gary Heiting describes how a contrast sensitivity test can detect vision problems that might not show up on a conventional eye ... Contrast sensitivity testing. Contrast sensitivity testing often isnt included in a routine eye exam. Your eye doctor might ... Symptoms of reduced contrast sensitivity. If you have low contrast sensitivity, you may have problems with night driving, ... Contrast sensitivity function (CSF). Detailed contrast sensitivity measurements that include both size (spatial frequency) and ...
more infohttps://www.allaboutvision.com/eye-exam/contrast-sensitivity.htm

The contrast sensitivity of retinal ganglion cells of the cat.  - PubMed - NCBIThe contrast sensitivity of retinal ganglion cells of the cat. - PubMed - NCBI

6. The way in which the sensitivity of an X-cell for a contrast-edge pattern varied with the distance of the edge from the ... The contrast sensitivity of retinal ganglion cells of the cat.. Enroth-Cugell C1, Robson JG. ... In every case it was found that the reciprocal of this relation, the contrast sensitivity function, could be satisfactorily ... 7. Reducing the retinal illumination produced changes in the contrast sensitivity function of an X-cell which suggested that ...
more infohttps://www.ncbi.nlm.nih.gov/pubmed/16783910?dopt=Abstract

Feeling blue, seeing gray: Reduced contrast sensitivity as a marker for depression | ScienceBlogsFeeling blue, seeing gray: Reduced contrast sensitivity as a marker for depression | ScienceBlogs

Feeling blue, seeing gray: Reduced contrast sensitivity as a marker for depression * facebook ... Isnt scoptic sensitivity syndrome - common among dyslexics - a hypersensitivity to contrast? I used to use coloured paper in ... The study shows that depressed people have reduced sensitivity to contrast, and therefore that they may perceive the world ... and to determine if any observed changes in the contrast sensitivity of depressed patients are due to changes in the eye or ...
more infohttps://scienceblogs.com/neurophilosophy/2010/07/22/feeling-blue-seeing-gray

Rhythmic Oscillations of Visual Contrast Sensitivity Synchronized with Action | Journal of NeuroscienceRhythmic Oscillations of Visual Contrast Sensitivity Synchronized with Action | Journal of Neuroscience

... or the improved contrast sensitivity and increased apparent contrast for the reach target location relative to locations in the ... Rhythmic Oscillations of Visual Contrast Sensitivity Synchronized with Action. Alice Tomassini, Donatella Spinelli, Marco ... Rhythmic Oscillations of Visual Contrast Sensitivity Synchronized with Action. Alice Tomassini, Donatella Spinelli, Marco ... Rhythmic Oscillations of Visual Contrast Sensitivity Synchronized with Action Message Subject (Your Name) has forwarded a page ...
more infohttps://www.jneurosci.org/content/35/18/7019?ijkey=dac49f021f711d1a99cd2e688e6179f709873420&keytype2=tf_ipsecsha

Contrast Sensitivity of Luminance FieldsContrast Sensitivity of Luminance Fields

... Bert W. Rust, ACMD Holly E. Rushmeier, Scientific Computing Environments Division ... This suggests a contrast sensitivity function of the form where r is the radial distance from the origin (measured in cycles ... Figure 11: The estimated contrast sensitivity function. Figure 12: The perceived luminance field. The two-dimensional Fourier ... The contrast sensitivity function is based on measured data taken radially in the vertical (. ) and oblique (. ) directions. It ...
more infohttps://math.nist.gov/mcsd/Reports/95/yearly/node27.html

Images perceived after chromatic or achromatic contrast sensitivity losses.Images perceived after chromatic or achromatic contrast sensitivity losses.

We simulate how subjects with losses in chromatic and achromatic contrast sensitivity perceive colored images by using the ... the algorithm would serve to simulate alterations both in the spectral sensitivities and in the contrast sensitivities of the ... Contrast Sensitivity / physiology*. Humans. Lighting. Mathematics. Models, Neurological*. Pattern Recognition, Visual / ... PURPOSE: We simulate how subjects with losses in chromatic and achromatic contrast sensitivity perceive colored images by using ...
more infohttp://www.biomedsearch.com/nih/Images-Perceived-After-Chromatic-Achromatic/20386355.html

Contrast sensitivity | definition of contrast sensitivity by Medical dictionaryContrast sensitivity | definition of contrast sensitivity by Medical dictionary

What is contrast sensitivity? Meaning of contrast sensitivity medical term. What does contrast sensitivity mean? ... Looking for online definition of contrast sensitivity in the Medical Dictionary? contrast sensitivity explanation free. ... Table S1 Relationship between contrast sensitivity and contrast threshold (contrast sensitivity = 1/contrast threshold). ... See contrast sensitivity chart; contrast sensitivity function; spurious resolution; Arden grating test; Vistech.. ...
more infohttps://medical-dictionary.thefreedictionary.com/contrast+sensitivity

Spatiotemporal Contrast Sensitivity after Acute Alcohol IngestionSpatiotemporal Contrast Sensitivity after Acute Alcohol Ingestion

Average contrast sensitivity (+/- 1 SE) as a function of spatial frequency. Sensitivity is calculated as the reciprocal of the ... Average contrast sensitivity (+/- 1 SE) as a function of spatial frequency for four temporal modulation rates. Each panel shows ... Spatiotemporal Contrast Sensitivity after Acute Alcohol Ingestion. Brian Timney and Pauline Pearson. Department of Psychology, ... Contrast sensitivity for stationary sine-wave gratings was measured for spatial frequencies of 0.5, 0.75, 1, 2, 4, 6, 8, 12 and ...
more infohttp://druglibrary.org/schaffer/MISC/driving/s30p4.htm

Rapid Simultaneous Enhancement of Visual Sensitivity and Perceived Contrast during Saccade Preparation | Journal of NeuroscienceRapid Simultaneous Enhancement of Visual Sensitivity and Perceived Contrast during Saccade Preparation | Journal of Neuroscience

... we simultaneously assessed the effects of saccade preparation on both contrast sensitivity and perceived contrast. ... 2000) Spatial covert attention increases contrast sensitivity across the CSF: support for signal enhancement. Vision Res 40: ... C, Individual contrast reports and PSEs. D, Average perceived contrast as a function of time relative to saccade onset. All ... Rapid Simultaneous Enhancement of Visual Sensitivity and Perceived Contrast during Saccade Preparation. Martin Rolfs and Marisa ...
more infohttp://www.jneurosci.org/content/32/40/13744

Visual resolution and contrast sensitivity in two benthic sharks | Journal of Experimental BiologyVisual resolution and contrast sensitivity in two benthic sharks | Journal of Experimental Biology

... contrast in H. portusjacksoni and C. punctatum respectively. Contrast sensitivity was higher than in other vertebrates with a ... Visual resolution and contrast sensitivity in two benthic sharks. Laura A. Ryan, Nathan S. Hart, Shaun P. Collin, Jan M. Hemmi ... Visual resolution and contrast sensitivity in two benthic sharks. Laura A. Ryan, Nathan S. Hart, Shaun P. Collin, Jan M. Hemmi ... Visual resolution and contrast sensitivity in two benthic sharks. Laura A. Ryan, Nathan S. Hart, Shaun P. Collin, Jan M. Hemmi ...
more infohttp://jeb.biologists.org/content/early/2016/10/21/jeb.132100

Evaluation of Contrast Sensitivity, Chromatic Vision, and Reading Ability in Patients with Primary Open Angle GlaucomaEvaluation of Contrast Sensitivity, Chromatic Vision, and Reading Ability in Patients with Primary Open Angle Glaucoma

... Maria P ... Contrast sensitivity was measured using the Pelli-Robson Chart and the CSV1000E test. Chromatic vision was evaluated using the ... To compare contrast sensitivity, acquired color vision deficiency, and reading ability in patients with glaucoma at different ... Contrast sensitivity was significantly worse in patients with moderate glaucoma compared to those with early-stage glaucoma. ...
more infohttps://www.hindawi.com/journals/joph/2016/7074016/abs/

The effect of pterygium surgery on contrast sensitivity and corneal to | OPTHThe effect of pterygium surgery on contrast sensitivity and corneal to | OPTH

Spatial contrast sensitivity testing was performed using VCTS 6500. Differences between preoperative and postoperative values ... To investigate the effect of pterygium surgery on corneal topography and contrast sensitivity.Patient and methods: The IRB ... The effect of pterygium surgery on contrast sensitivity and corneal topographic changes Joo Youn Oh, Won Ryang WeeDepartment of ... The effect of pterygium surgery on contrast sensitivity and corneal topographic changes. ...
more infohttps://www.dovepress.com/the-effect-of-pterygium-surgery-on-contrast-sensitivity-and-corneal-to-peer-reviewed-article-OPTH

Frontiers | Binocular Summation and Suppression of Contrast Sensitivity in Strabismus, Fusion and Amblyopia | Human NeuroscienceFrontiers | Binocular Summation and Suppression of Contrast Sensitivity in Strabismus, Fusion and Amblyopia | Human Neuroscience

The contrast sensitivity function (CSF) generally takes longer to assess than visual acuity, but it is better correlated with ... Conclusions: We conclude that monocular and binocular contrast sensitivity deficits define important characteristics of ... We conclude that monocular and binocular contrast sensitivity deficits define important characteristics of amblyopia a... ... Binocular contrast summation exceeded probability summation in controls, but not in subjects with amblyopia (with or without ...
more infohttps://www.frontiersin.org/articles/10.3389/fnhum.2019.00234/full

The paradox of relaxation training: Relaxation induced anxiety and mediation effects of negative contrast sensitivity in...The paradox of relaxation training: Relaxation induced anxiety and mediation effects of negative contrast sensitivity in...

Our findings support the hypotheses that negative contrast sensitivity is the mediator of both GAD and MDD in predicting RIA. ... Negative contrast sensitivity fully mediated GAD and partially mediated MDD in predicting RIA. ... This was followed by the assessment of their negative contrast sensitivity. After this, participants engaged again with ... The paradox of relaxation training: Relaxation induced anxiety and mediation effects of negative contrast sensitivity in ...
more infohttps://www.ncbi.nlm.nih.gov/pubmed/31450137

Frontiers | Declined contrast sensitivity of neurons along the visual pathway in aging cats | Frontiers in Aging NeuroscienceFrontiers | Declined contrast sensitivity of neurons along the visual pathway in aging cats | Frontiers in Aging Neuroscience

Reduced contrast sensitivity of neurons in the three cortical areas was accompanied by enhanced maximal visual response, ... Reduced contrast sensitivity of neurons in the three cortical areas was accompanied by enhanced maximal visual response, ... In the current study, the contrast response function, one of the most important properties of neurons from early visual areas ... In the current study, the contrast response function, one of the most important properties of neurons from early visual areas ...
more infohttps://www.frontiersin.org/articles/10.3389/fnagi.2014.00163/full

Visual Outcomes And Contrast Sensitivity After Myopic Wavefront-Optimized Lasik With Nexisvision Shield Or Bandage Contact Lens...Visual Outcomes And Contrast Sensitivity After Myopic Wavefront-Optimized Lasik With Nexisvision Shield Or Bandage Contact Lens...

Contrast Sensitivity [ Time Frame: Immediate, 30 minutes, 1 hour, 2 hour, and 4 hours ]. Change in contrast sensitivity ... Visual Outcomes And Contrast Sensitivity After Myopic Wavefront-Optimized Lasik With Nexisvision Shield Or Bandage Contact Lens ... Historically, LASIK has been reported to decrease contrast sensitivity post operatively and patients have been advised to take ... Evaluate visual outcomes and contrast sensitivity for subjects undergoing bilateral myopic LASIK with a Nexisvision Shield or ...
more infohttps://clinicaltrials.gov/show/NCT01706237

Visual Outcomes And Contrast Sensitivity After Myopic Wavefront-Optimized Lasik With Nexisvision Shield Or Bandage Contact Lens...Visual Outcomes And Contrast Sensitivity After Myopic Wavefront-Optimized Lasik With Nexisvision Shield Or Bandage Contact Lens...

Contrast Sensitivity [ Time Frame: Immediate, 30 minutes, 1 hour, 2 hour, and 4 hours ]. Change in contrast sensitivity ... Visual Outcomes And Contrast Sensitivity After Myopic Wavefront-Optimized Lasik With Nexisvision Shield Or Bandage Contact Lens ... Historically, LASIK has been reported to decrease contrast sensitivity post operatively and patients have been advised to take ... Evaluate visual outcomes and contrast sensitivity for subjects undergoing bilateral myopic LASIK with a Nexisvision Shield or ...
more infohttps://clinicaltrials.gov/ct2/show/NCT01706237

A 128-128 1.5% Contrast Sensitivity 0.9% FPN 3 µs Latency 4 mW Asynchronous Frame-Free Dynamic Vision Sensor Using...A 128-128 1.5% Contrast Sensitivity 0.9% FPN 3 µs Latency 4 mW Asynchronous Frame-Free Dynamic Vision Sensor Using...

Dynamic Vision Sensors (DVS) have recently appeared as a new paradigm for vision sensing and processing. They feature unique characteristics such as contra
more infohttp://ieeexplore.ieee.org/document/6407468/keywords?reload=true

Contrast sensitivity measurement in evaluations in visual symptoms caused by exposure to triethylamineContrast sensitivity measurement in evaluations in visual symptoms caused by exposure to triethylamine

Contrast sensitivity and visual acuity were measured by optotype figures at full contrast, 2.5% contrast, and 0.6% contrast. ... The contrast sensitivity of the core makers decreased significantly at both 2.5% and 0.6% contrast during the working day. In ... The contrast sensitivity of the core makers was measured on Monday and Friday of the same week both before and immediately ... The changes in contrast sensitivity were used for the analysis. The results of binocular vision and the results of the dominant ...
more infohttp://connection.ebscohost.com/c/articles/8002943/contrast-sensitivity-measurement-evaluations-visual-symptoms-caused-by-exposure-triethylamine

Analyses of contrast sensitivity assessments over time: A pilot study | IOVS | ARVO JournalsAnalyses of contrast sensitivity assessments over time: A pilot study | IOVS | ARVO Journals

Analyses of contrast sensitivity assessments over time: A pilot study Xi Chen; Luis Lesmes; Jennifer Wallis; Thomas Wallis; ... Analyses of contrast sensitivity assessments over time: A pilot study You will receive an email whenever this article is ... Purpose: The contrast sensitivity function (CSF) provides a useful functional endpoint for development of ophthalmic drugs and ... Methods: In 5 subjects with corrected-to-normal vision (ages ranging from 20 to 57), we tested contrast sensitivity weekly over ...
more infohttps://iovs.arvojournals.org/article.aspx?articleid=2147483

Contrast Sensitivity After Wavefront-Guided and Wavefront-Optimized PRK and LASIK for Myopia and Myopic AstigmatismContrast Sensitivity After Wavefront-Guided and Wavefront-Optimized PRK and LASIK for Myopia and Myopic Astigmatism

To compare contrast sensitivity among participants undergoing wavefront-guided or wavefront-optimized photorefractive ... high contrast and small letter contrast sensitivity, uncorrected postoperative contrast sensitivity function, and uncorrected ... high contrast and small letter contrast sensitivity, uncorrected postoperative contrast sensitivity function, and uncorrected ... Because the Super Vision Test assesses high spatial frequency contrast sensitivity and high contrast visual acuity,21. contrast ...
more infohttps://www.healio.com/ophthalmology/journals/jrs/2018-9-34-9/%7Bbcedefaf-8212-4aba-bbdb-cef0ae4edf34%7D/contrast-sensitivity-after-wavefront-guided-and-wavefront-optimized-prk-and-lasik-for-myopia-and-myopic-astigmatism

Determining Contrast Sensitivity Functions for LEDs | Solid State Lighting | Programs | LRCDetermining Contrast Sensitivity Functions for LEDs | Solid State Lighting | Programs | LRC

... it necessary to have corresponding contrast sensitivity functions (CSFs), which describe the contrast sensitivity of the visual ... 1: Contrast sensitivity functions derived for 2-degree sinusoidal gratings at a luminance of 45 cd/m2 for red (625 nm), green ( ... 3: Contrast sensitivity functions derived for 10-degree sinusoidal gratings at a luminance of 45 cd/m2 for red (625 nm), green ... 2: Contrast sensitivity functions derived for 2-degree sinusoidal gratings at typical luminance values (red: 125 cd/m2, green: ...
more infohttp://www.lrc.rpi.edu/programs/solidstate/cr_ContrastFunctions.asp

Visual acuity and contrast sensitivity following Descemet stripping automated endothelial keratoplasty | British Journal of...Visual acuity and contrast sensitivity following Descemet stripping automated endothelial keratoplasty | British Journal of...

If patients could recognise themselves, or anyone else could recognise a patient from your description, please obtain the patients written consent to publication and send them to the editorial office before submitting your response [Patient consent forms] ...
more infohttps://bjo.bmj.com/content/100/3/307.responses
  • The PERG is evoked by viewing patterned stimuli and, in this case, its size is indicative of contrast gain. (scienceblogs.com)
  • To address these important questions, the present study measures the contrast sensitivity of brief visual stimuli unrelated to the instructed action, at different times during motor planning and execution. (jneurosci.org)
  • This study estimates contrast sensitivity and spatial resolution of two species of benthic sharks, the Port Jackson shark, Heterodontus portusjacksoni , and the brown-banded bamboo shark, Chiloscyllium punctatum, by recording eye movements in response to optokinetic stimuli. (biologists.org)
  • In the current study, we examined how neurons at different stages in the visual pathway of cats responded to variations in the contrast of sine wave grating stimuli. (frontiersin.org)
  • We also found generalization of PL to different stimuli and tasks: contrast sensitivity for both trained and untrained spatial frequencies, visual acuity for Sloan letters, and foveal crowding, and partially for Vernier acuity. (iospress.com)
  • To gain a more complete picture of the influence of alcohol on visual performance we measured contrast sensitivity for a range of spatial and temporal frequencies in individuals with moderate blood alcohol levels. (druglibrary.org)
  • In the current study, the contrast response function, one of the most important properties of neurons from early visual areas to high brain areas, was systematically compared along the visual pathway, including the lateral geniculate nucleus (LGN), early visual cortices (A17 and A18), and posteromedial lateral suprasylvian cortex (PMLS, analog to the medial temporal area (MT) in monkeys) of young and old cats. (frontiersin.org)
  • CONCLUSIONS: The simulations allow us to learn about the different types of distortions that can be experienced by a subject with impaired contrast sensitivities (blur, haloes, color shifts, local or global contrast, brightness and colorfulness reductions, etc.) and highlight the difficulties arising when trying to predict the quality of the final image from the losses in the individual mechanisms. (biomedsearch.com)
  • Conclusions: The blurred vision caused by exposure to TEA can be documented by measuring contrast sensitivity. (ebscohost.com)
  • These bars can vary in width ( spatial frequency ) as well as contrast from target to target, to give a more thorough evaluation of how sensitive your eyes are to differences in contrast. (allaboutvision.com)
  • However, there were no significant differences when comparing the four groups for high contrast sensitivity ( P = .22) or small letter contrast sensitivity ( P = .06). (healio.com)
  • There were not significant differences between the binocular contrast sensitivity measured with and without glare. (arvojournals.org)
  • While the effect of spatial frequency and contrast on position control is similar between the species, ground speed is differently affected by these variables. (biologists.org)
  • Considering the important effect of various colors of sunglasses on visual performance, this study was aimed to evaluate the effect of different colors of sun glasses on visual acuity, contrast sensitivity , stereopsis and color vision. (thefreedictionary.com)
  • Evaluate visual outcomes and contrast sensitivity for subjects undergoing bilateral myopic LASIK with a Nexisvision Shield or bandage contact lens placed postoperatively. (clinicaltrials.gov)
  • For clinical studies using contrast sensitivity endpoints, it is critical to evaluate trends over time. (arvojournals.org)
  • The study shows that depressed people have reduced sensitivity to contrast, and therefore that they may perceive the world differently from others. (scienceblogs.com)
  • PURPOSE: We simulate how subjects with losses in chromatic and achromatic contrast sensitivity perceive colored images by using the spatiochromatic corresponding pair algorithm. (biomedsearch.com)
  • It has long been known, for example, that reserpine, a drug which is prescribed for psychosis and hypertension and which induces depression in humans, causes excessive sensitivity to light in various animals. (scienceblogs.com)
  • Results:The results showed that perceptual training reduced the target's contrast-detection thresholds more for the longest target-to-flanker separation (i.e., 8λ). (iospress.com)
  • Conversely, some people achieve better contrast sensitivity and night vision after LASIK, compared with their vision with glasses or contact lenses before the procedure. (allaboutvision.com)
  • Low vision often causes decreased contrast sensitivity as well as reduced resolution, making it more difficult to see low-contrast images on SVD devices. (thefreedictionary.com)
  • Our results suggest that vision in sharks is not 'poor' as previously suggested, but optimised for contrast detection rather than spatial resolution. (biologists.org)
  • Objectives: To determine whether blurred vision caused by exposure to triethylamine (TEA) can be detected by the measurement of contrast sensitivity. (ebscohost.com)
  • To understand the visual limits of flight control in bees, which rely heavily on vision to control flight, and to explore whether they vary between species, we tested how changes in spatial resolution and contrast sensitivity affect the speed and position control of the Asian and European honeybees ( Apis cerana and Apis mellifera ). (biologists.org)
  • The visual resolution that limits the detection and use of optic flow for flight control in both species of honeybee is lower than the previously anatomically determined resolution and differs from object detection limits of A. mellifera , providing evidence that the limits of spatial resolution and contrast sensitivity are highly tuned to the particular behavioural task of a species. (biologists.org)
  • Therefore, there is a need for enhanced sensitivity/specificity of detection for small lung cancers. (pubmedcentralcanada.ca)
  • Here we examine the ability of the scL-gad-d complex to increase the sensitivity of detection of lung metastases. (pubmedcentralcanada.ca)
  • Because of its tumor targeting specificity, deliver of an MRI contrast agent via this nanocomplex has potential for use as an agent that can identify small lung cancers, thus improving early detection and possibly increasing survival. (pubmedcentralcanada.ca)
  • Objective:We measured the extent and duration of generalization effects to various spatial tasks (i.e., visual acuity, Vernier acuity, and foveal crowding) through PL on the target's contrast detection. (iospress.com)
  • The authors conclude that it is important for a contrast sensitivity testing method to have strong reliability to differentiate normal from abnormal and to determine whether progression is real. (aao.org)
  • Here we reveal this missing link by showing that saccade preparation increases the perceived signal strength-perceived contrast-consistent with enhanced neural representations of visual information at the saccade target. (jneurosci.org)
  • These filters, except for the global scaling, are the subject's contrast sensitivity functions measured along the cardinal directions of the color space. (biomedsearch.com)
  • We examined mediation effects of negative contrast on the relationship between diagnostic status and RIA. (nih.gov)
  • Peak values of the CSFs occur at smaller spatial frequencies compared with the 2-degree field, and the values of contrast sensitivity for the 10-degree case are greater at all spatial frequencies compared with the 2-degree case. (rpi.edu)
  • Contrast sensitivity was higher than in other vertebrates with a similar spatial resolving power, which may reflect an adaptation to the relatively low contrast encountered in aquatic environments. (biologists.org)