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.
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.
A series of tests used to assess various functions of the eyes.
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)
The minimum amount of stimulus energy necessary to elicit a sensory response.
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.
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).
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.
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.
Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)
The process in which light signals are transformed by the PHOTORECEPTOR CELLS into electrical signals which can then be transmitted to the brain.
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.
Investigative technique commonly used during ELECTROENCEPHALOGRAPHY in which a series of bright light flashes or visual patterns are used to elicit brain activity.
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.
The total area or space visible in a person's peripheral vision with the eye looking straightforward.
Mental process to visually perceive a critical number of facts (the pattern), such as characters, shapes, displays, or designs.
The awareness of the spatial properties of objects; includes physical space.
The point or frequency at which all flicker of an intermittent light stimulus disappears.
Set of cell bodies and nerve fibers conducting impulses from the eyes to the cerebral cortex. It includes the RETINA; OPTIC NERVE; optic tract; and geniculocalcarine tract.
The electric response evoked in the cerebral cortex by visual stimulation or stimulation of the visual pathways.
The sensory discrimination of a pattern shape or outline.
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)
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.
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)
The aperture in the iris through which light passes.
The blending of separate images seen by each eye into one composite image.
Type of vision test used to determine COLOR VISION DEFECTS.
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.
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).
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)
Artificial implanted lenses.
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 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.).
Differential response to different stimuli.
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.
Method of measuring and mapping the scope of vision, from central to peripheral of each eye.
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.
The selecting and organizing of visual stimuli based on the individual's past experience.
Normal nystagmus produced by looking at objects moving across the field of vision.
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.
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.
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.
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.
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.
Adjustment of the eyes under conditions of low light. The sensitivity of the eye to light is increased during dark adaptation.
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).
Awareness of oneself in relation to time, place and person.
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 of LIGHT effected by the media of the EYE.
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.
Deviations from the average or standard indices of refraction of the eye through its dioptric or refractive apparatus.
Images seen by one eye.
The dioptric adjustment of the EYE (to attain maximal sharpness of retinal imagery for an object of regard) referring to the ability, to the mechanism, or to the process. Ocular accommodation is the effecting of refractive changes by changes in the shape of the CRYSTALLINE LENS. Loosely, it refers to ocular adjustments for VISION, OCULAR at various distances. (Cline et al., Dictionary of Visual Science, 4th ed)
The real or apparent movement of objects through the visual field.
Area of the OCCIPITAL LOBE concerned with the processing of visual information relayed via VISUAL PATHWAYS.
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.
Processes and properties of the EYE as a whole or of any of its parts.
That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.
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.
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)
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)
Persons with loss of vision such that there is an impact on activities of daily living.
Perception of three-dimensionality.
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.
A condition of an inequality of refractive power of the two eyes.
The positioning and accommodation of eyes that allows the image to be brought into place on the FOVEA CENTRALIS of each eye.
The absence or restriction of the usual external sensory stimuli to which the individual responds.
The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.
Glaucoma in which the angle of the anterior chamber is open and the trabecular meshwork does not encroach on the base of the iris.
A long-acting injectable antipsychotic agent used for chronic schizophrenia.
Measurement of the various properties of light.
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)
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.
Lenses designed to be worn on the front surface of the eyeball. (UMDNS, 1999)
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)
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.
Continuation of visual impression after cessation of stimuli causing the original image.
The study of the physiological basis of human and animal behavior.
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.
Theoretical representations that simulate psychological processes and/or social processes. These include the use of mathematical equations, computers, and other electronic equipment.
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.
The removal of a cataractous CRYSTALLINE LENS from the eye.
The sensory interpretation of the dimensions of objects.
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. 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.
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.
The visually perceived property of objects created by absorption or reflection of specific wavelengths of light.
An exudate between the RETINA and CHOROID from various sources including the vitreous cavity, SUBARACHNOID SPACE, or abnormal vessels.
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)
The normal decreasing elasticity of the crystalline lens that leads to loss of accommodation.
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.
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.
Recording of electric potentials in the retina after stimulation by light.
Elements of limited time intervals, contributing to particular results or situations.
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.
The interference of one perceptual stimulus with another causing a decrease or lessening in perceptual effectiveness.
A family of nonmetallic, generally electronegative, elements that form group 17 (formerly group VIIa) of the periodic table.
Absence of the crystalline lens resulting from cataract extraction.
Focusing on certain aspects of current experience to the exclusion of others. It is the act of heeding or taking notice or concentrating.
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)
Devices for examining the interior of the eye, permitting the clear visualization of the structures of the eye at any depth. (UMDNS, 1999)
The administration of substances into the eye with a hypodermic syringe.
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.
Lack of correspondence between the way a stimulus is commonly perceived and the way an individual perceives it under given conditions.
A type of refractive surgery of the CORNEA to correct MYOPIA and ASTIGMATISM. An EXCIMER LASER is used directly on the surface of the EYE to remove some of the CORNEAL EPITHELIUM thus reshaping the anterior curvature of the cornea.
The smallest difference which can be discriminated between two stimuli or one which is barely above the threshold.
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.
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.
Diseases affecting the eye.
The time from the onset of a stimulus until a response is observed.
A genus, commonly called budgerigars, in the family PSITTACIDAE. In the United States they are considered one of the five species of PARAKEETS.
Presence of an intraocular lens after cataract extraction.
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.
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.
A procedure to surgically correct REFRACTIVE ERRORS by cutting radial slits into the CORNEA to change its refractive properties.
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.
Hereditary, progressive degeneration of the neuroepithelium of the retina characterized by night blindness and progressive contraction of the visual field.
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.
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.
Assessment of psychological variables by the application of mathematical procedures.
A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.
The organ of sight constituting a pair of globular organs made up of a three-layered roughly spherical structure specialized for receiving and responding to light.
A 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.
A condition in which the intraocular pressure is elevated above normal and which may lead to glaucoma.
Signals for an action; that specific portion of a perceptual field or pattern of stimuli to which a subject has learned to respond.
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.
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.
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)
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)
An oval area in the retina, 3 to 5 mm in diameter, usually located temporal to the posterior pole of the eye and slightly below the level of the optic disk. It is characterized by the presence of a yellow pigment diffusely permeating the inner layers, contains the fovea centralis in its center, and provides the best phototropic visual acuity. It is devoid of retinal blood vessels, except in its periphery, and receives nourishment from the choriocapillaris of the choroid. (From Cline et al., Dictionary of Visual Science, 4th ed)
The pressure of the fluids in the eye.
The functional superiority and preferential use of one eye over the other. The term is usually applied to superiority in sighting (VISUAL PERCEPTION) or motor task but not difference in VISUAL ACUITY or dysfunction of one of the eyes. Ocular dominance can be modified by visual input and NEUROTROPHIC FACTORS.
A 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)
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.
Voluntary or reflex-controlled movements of the eye.
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.
Fluid accumulation in the outer layer of the MACULA LUTEA that results from intraocular or systemic insults. It may develop in a diffuse pattern where the macula appears thickened or it may acquire the characteristic petaloid appearance referred to as cystoid macular edema. Although macular edema may be associated with various underlying conditions, it is most commonly seen following intraocular surgery, venous occlusive disease, DIABETIC RETINOPATHY, and posterior segment inflammatory disease. (From Survey of Ophthalmology 2004; 49(5) 470-90)
The 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.
The continuous sequential physiological and psychological maturing of an individual from birth up to but not including ADOLESCENCE.
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.
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)
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.
The blood vessels which supply and drain the RETINA.
Methods and procedures for the diagnosis of diseases of the eye or of vision disorders.
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.
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)
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.)
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.
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.
The use of green light-producing LASERS to stop bleeding. The green light is selectively absorbed by HEMOGLOBIN, thus triggering BLOOD COAGULATION.
A pathological process consisting of the formation of new blood vessels in the CHOROID.
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)
The coordination of a sensory or ideational (cognitive) process and a motor activity.
Application of computer programs designed to assist the physician in solving a diagnostic problem.
Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.
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.
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)

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 ...
Mars Letter Contrast Sensitivity Test. Identifying functional losses in low contrast perception (often associated with glare sensitivity). Buy online.
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 ...
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).
Rabin Contrast Sensitivity (CS) Test. Contrast sensitivity test comparable to the Small Letter Contrast Test. Buy online from Precision Vision!
To evaluate the effects on contrast sensitivity (CS) measurements of intravitreal bevacizumab injections associated with standard metabolic control in eyes
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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Contrast response functions (CRFs) for the VEP were obtained with a Discrete Fourier Transform (DFT) technique employing swept contrast gratings. VEP CRFs in infants were found to have a form similar to those observed in adults, being linear functions of log contrast over a range of near-threshold c …
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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 ...
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 ...
Measuring eyesight for drivers involves several different important categories of vision. A positive result of Visual Acuity Screening is that it ensures that signs and other critical markings in the roadway environment (lane markings) would be adequately legible to most drivers. Thus a minimum level to driving in Ireland, with 2 functioning eyes, is 6/12 for Group 1 applicants (A1, A, B,EB, M or W) and 6/7.5 for Group 2 applicants (C1, C, EC1, EC, D1, D, ED1, ED), trucks, buses etc Contrast sensitivity refers to the amount of contrast a person needs in order to detect or identify an object or pattern in varying light levels. Think of trying to read the eye chart through a fog. A fog that is getting more and more dense. A person who has poor contrast sensitivity requires a higher contrast to see objects or patterns from a person who has good contrast sensitivity i.e. they need a more stark black on white difference. Impairment of contrast sensitivity can result from a number of different eye and ...
TY - CHAP. T1 - Fixation, contrast sensitivity and childrens reading. AU - Cornelissen, P. PY - 1993. Y1 - 1993. M3 - Chapter. SN - 0-444-89949-9. VL - 3. T3 - Studies In Visual Information Processing. SP - 139. EP - 162. BT - Facets of dyslexia and its remediation. ER - ...
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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Test for quick measurement of low contrast visual acuity at 25%, 10%, 5%, 2.5%, and 1.25% contrast by measuring the distance where the symbols are seen. 10M symbols correspond to visual acuity 0.10 at 1 m, 0.05 at 0.5 m and 0.3 at 3 m. VA values are thus easy to calculate. Test includes a ...
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
This dataset contains contrast measurements at luminances from 0.02 cd/m^2 (mesopic) to 7000 cd/m^2 (photopic). The stimuli were Gabor patches at f = 0.5, 1, 2, 4, 6 cpd in three colour directions. Please refer to README.md for further details. For more information, please also see the project page: https://www.cl.cam.ac.uk/research/rainbow/projects/hdr-csf ...
Dynamic Vision Sensors (DVS) have recently appeared as a new paradigm for vision sensing and processing. They feature unique characteristics such as contra
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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
TY - JOUR. T1 - Differential impact of exogenous and endogenous attention on the contrast sensitivity function across eccentricity. AU - Jigo, Michael. AU - Carrasco, Marisa. N1 - Funding Information: We thank Antoine Barbot, Rachel Denison, Antonio Fern?ndez, David Heeger, Michael Landy, and Jonathan Winawer for their helpful comments, as well as Maya Mosley for assistance in data collection. Funded by National Institutes of Health R01-EY019693 and NEI R21-EY026185 to MC. Publisher Copyright: © 2020 Association for Research in Vision and Ophthalmology Inc. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.. PY - 2020. Y1 - 2020. N2 - Both exogenous and endogenous covert spatial attention enhance contrast sensitivity, a fundamental measure of visual function that depends substantially on the spatial frequency and eccentricity of a stimulus. Whether and how each type of attention systematically improves contrast sensitivity across spatial frequency and eccentricity are fundamental to ...
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 ...
Fingerprint Dive into the research topics of Visual function of a patient with advanced adrenoleukodystrophy: Comparison of luminance and color contrast sensitivities. Together they form a unique fingerprint. ...
Purpose: AMD is one of the leading causes of vision loss globally. Since color vision impairment is often one of the first symptoms of retinal disease, earlier AMD detection may be possible using color vision screenings. This potential detection could result in earlier treatment and decreased progression of the disease before irreversible damage to sight occurs.. Methods: Patients from the Illinois Eye Institute and Chicago Eye Institute were asked to perform the King Devick Variable Color Contrast Sensitivity(VCCSC) iPad test monocularly at their best corrected near visual acuity with black, red, blue, green, and yellow letters at various contrast levels (100%,75%,50%, and 25%). Identification accuracy (out of 5 letters) was recorded as both color and contrast changed.. Results: Data was analyzed using SPSS v21. All values are presented as means±SEM. The control group (n=35) age 50-79 years (46% male, 54% female). The non-exudative (NE) AMD(n=26) age 60-82 years (67% male, 33% female). A ...
At the recent ESCRS meeting in London, Dr David Evans participated as a faculty member in a course about contrast sensitivity (CS). Dr Gregory Pamel was the Course Director. During the course, Dr Evans covered the scientific basis of testing contrast sensitivity with sine-wave gratings and how it compares to standard visual acuity as a measure for real-world vision. Dr Pamel provided detailed information about the clinical significance of contrast sensitivity testing for cataract documentation, evaluation of refractive surgery outcomes and the use of CS testing to aid in evaluating the need for and results of re-treatments after initial refractive surgery. He also provided the most recent CS findings for new methods of presbyopia correction, including FDA trial data from ReVision Optics and AcuFocus. Dr Pamel then shared his thoughts about the importance of preserving patient quality of vision when correcting presbyopia and how CS testing is an important metric to determine the best outcomes. ...
The perception of speed is influenced by visual contrast. In primary visual cortex (V1), an early stage in the visual perception pathway, the neural tuning to speed is directly related to the neural tuning to temporal frequency of stimulus changes. The influence of contrast on speed perception can be caused by the joint dependency of neural responses in V1 on temporal frequency and contrast. Here, we investigated how tuning to contrast and temporal frequency in V1 of anesthetized mice are related. We found that temporal frequency tuning is contrast-dependent. V1 was more responsive at lower temporal frequencies than the dLGN, consistent with previous work at high contrast. The temporal frequency tuning moves toward higher temporal frequencies with increasing contrast. The low half-maximum temporal frequency does not change with contrast. The Heeger divisive normalization equation provides a good fit to many response characteristics in V1, but does not fit the dependency of temporal frequency and
TY - JOUR. T1 - Reaction time to motion onset of luminance and chromatic gratings is determined by perceived speed. AU - Burr, David C.. AU - Fiorentini, Adriana. AU - Morrone, Concetta. PY - 1998/12. Y1 - 1998/12. N2 - We measured reaction times for detecting motion onset for sinusoidal gratings whose contrast was modulated in either luminance or chromaticity, for various drift rates and contrasts. In general, reaction times to chromatic gratings were slower than to luminance gratings of matched cone contrast, but the difference in response depended critically on both contrast and speed. At high image speeds there was virtually no difference, whereas at low speeds, the difference was pronounced, especially at low contrasts. At high image speeds there was little dependence of reaction times on contrast (for either luminance or colour), whereas at low speeds the dependence was greater, particularly for chromatic stimuli. This pattern of results is reminiscent of those found for apparent speed of ...
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 ...
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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
Purpose: To investigate whether a small angle glare test in a clinical setting can produce and detect a significant decrease in contrast sensitivity with age in normal young and elderly eyes. Methods: Contrast sensitivity (CS), with and without glare, was measured in 20 subjects. The subjects were all fully corrected. CS was measured using the Freiburg Visual Acuity & Contrast Test (FrACT) software running on a Macintosh imac (CRT). In our set-up the software uses a 4AFC-method, and the test distance was 4 meters. Glare was induced by a Fostec DCR® II light source with a randomised fiberoptical bundle mirrored into the centre of a Landolt C test target. Full test symmetry was accomplished by using this glare set-up. The test target and the glare source subtended an angle of about 1.3° and 0.2° respectively, yielding a 0.5° glare angle. The target mean luminance was 61 cd/m2 and the illuminance at the eye was 15 lux with glare. Results: We measured 20 subjects (20 to 59 yrs) with no known ...
It oversees the development of new device technologies such as sources and detectors as components, active elements such as modulators/switches, integration of optical components to perform various functions, development of active optical system/subsystem technologies including hardware, propagation considerations, and beam manipulation techniques.
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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…
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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 ...
Computational modeling is a useful method for generating hypotheses about the contributions of impaired neurobiological mechanisms, and their interactions, to psychopathology. Modeling is being increasingly used to further our understanding of schizophrenia, but to date, it has not been applied to questions regarding the common perceptual disturbances in the disorder. In this article, we model aspects of low-level visual processing and demonstrate how this can lead to testable hypotheses about both the nature of visual abnormalities in schizophrenia and the relationships between the mechanisms underlying these disturbances and psychotic symptoms. Using a model that incorporates retinal, lateral geniculate nucleus (LGN), and V1 activity, as well as gain control in the LGN, homeostatic adaptation in V1, lateral excitation and inhibition in V1, and self-organization of synaptic weights based on Hebbian learning and divisive normalization, we show that (a) prior data indicating ...
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.
We used a cross-modal dual task to examine how changing visual-task demands influenced auditory processing, namely auditory thresholds for amplitude- and frequency-modulated sounds. Observers had to attend to two consecutive intervals of sounds and report which interval contained the auditory stimulus that was modulated in amplitude (Experiment 1) or frequency (Experiment 2). During auditory-stimulus presentation, observers simultaneously attended to a rapid sequential visual presentation-two consecutive intervals of streams of visual letters-and had to report which interval contained a particular color (low load, demanding less attentional resources) or, in separate blocks of trials, which interval contained more of a target letter (high load, demanding more attentional resources). We hypothesized that if attention is a shared resource across vision and audition, an easier visual task should free up more attentional resources for auditory processing on an unrelated task, hence improving auditory
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.. ...
Development of Population since 1875 within the Current Boundaries (Blue Line: Population; Dotted Line: Comparison to Population Development of Brandenburg state; Grey Background: Time of Nazi rule; Red Background: Time of Communist rule) Development of Population since 1875 within the Current Boundaries (Blue Line: Population; Dotted Line: Comparison to Population Development of Brandenburg state; Grey Background: Time of Nazi rule; Red Background: Time of Communist rule) Recent Population Development (Blue Line) and Forecasts Recent Population Development (Blue Line) and Forecasts Detailed data sources are to be found in the Wikimedia Commons
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
In this report we present a confocal Raman system to identify the unique spectral features of two proteins, Interleukin-10 and Angiotensin Converting Enzyme. Characteristic Raman spectra were successfully acquired and identified for the first time to our knowledge, showing the potential of Raman spectroscopy as a non-invasive investigation tool for biomedical applications.
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 ...
... 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 ...
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] ...
"Contrast sensitivity" (PDF). LEA-Test Ltd. Retrieved 21 July 2018. Kirschen DG, Laby DM (1 May 2006). "Sports Vision Testing: ... This produces a contrast of about 1% with the illumination of surrounding cones. The mechanism of detection is the ability to ... In low light (i.e., scotopic vision), cones do not have sufficient sensitivity and vision is subserved by rods. Spatial ... Under optimal conditions of good illumination, high contrast, and long line segments, the limit to vernier acuity is about 8 ...
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 ... At higher spatial frequencies, comprising finer and finer lines, contrast sensitivity decreases, until at about 40 cycles per ...
The NHK measured contrast sensitivity for the Rec. 2020 color space using Barten's equation which had previously been used to ...
"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 ...
"The Contrast Sensitivity of Retinal Ganglion Cells of the Cat". Journal of Physiology. 187 (3): 517-23. doi:10.1113/jphysiol. ... 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. The url for ...
Contrast sensitivity may be affected. The change in refractive index of the cornea may result in subtle refractive shifts, ...
Contrast sensitivity may be diminished. There could be an abnormal electroretinogram or visual evoked potentials. Neuron- ...
2 Visual Acuity, Contrast Sensitivity". University of Utah. Retrieved 19 July 2009.. ... Teller, D. "Linking Propositions" Barghout, Lauren (2014). Vision: How Global Perceptual Context Changes Local Contrast ...
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- ...
Do you have a low-contrast sensitivity? For example, do you have trouble seeing a gray car at dusk, a black car at night, or a ...
... and the sensitivity to contrast in sine wave stimuli is characterized by the contrast sensitivity function. Contrast ... PMID 20484523.CS1 maint: multiple names: authors list (link) Skottun, B. C., & Skoyles, J. R. (2007). "Contrast sensitivity and ... PMID 18549875.CS1 maint: multiple names: authors list (link) Slaghuis, W.L. (1998). "Contrast sensitivity for stationary and ... "Spatio-temporal luminance contrast sensitivity and visual backward masking in schizophrenia". Experimental Brain Research. 156 ...
Most older adult humans lose photopic spatial contrast sensitivity. Adults in their 70s require about three times more contrast ... "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 efficacy is 683 lm/W at a ... Candela Cone cell Contrast (vision) Mesopic vision Night vision Purkinje effect Photometry (optics) Photosensitive ganglion ...
Colored transparent insert discs to increase the contrast sensitivity. Semi-transparent occluder to block the non-aiming eye ... In contrast to most other eye glasses, shooting glasses usually only have one lens that corrects the ametropia of the dominant ...
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 ...
It was a stark contrast with his own heightened sensitivity. During this time in prison he began experiencing the epileptic ...
These improvement theories include the improvement of visual contrast sensitivity. Other developments include the ability to ...
Enroth-Cugell C, Robson JG (December 1966). "The contrast sensitivity of retinal ganglion cells of the cat". The Journal of ...
... 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, ...
ISBN 978-0-226-14576-1. Tootle, John; Friedlander, Michael (1989). Postnatal Development of the Spatial Contrast Sensitivity of ...
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 ...
This contrasted with the left hemisphere's lower level of sensitivity to variations. Although the concept of the left-brain ... In fMRI studies by Koutstaal the level of sensitivity of the right visual cortex with respect to the single exposure of an ... These studies illustrate the role of the left prefrontal cortex in exerting control over one's environment in contrast to the ...
The physiognomy and the surface of the sitter's skin are delicately rendered; delicacy and sensitivity contrast with the long, ...
... increases image processing speed and improves sensitivity, contrast and color reproduction." The main differences ...
In contrast, the sensitivity and specificity can be estimated from case-control studies. Suppose the fecal occult blood (FOB) ... sensitivity}}\times {\text{prevalence}}}{{\text{sensitivity}}\times {\text{prevalence}}+(1-{\text{specificity}})\times (1-{\ ... sensitivity × prevalence sensitivity × prevalence + ( 1 − specificity ) × ( 1 − prevalence ) {\displaystyle {\text{PPV}}={\frac ... In case-control studies the PPV has to be computed from sensitivity, specificity, but also including the prevalence: PPV = ...
Daw, N. W.; Enoch, J. M. (1973). "Contrast sensitivity, westheimer function and stiles-crawford effect in a blue cone ...
Patients with visual "snow" have normal equivalent input noise levels and contrast sensitivity. The causes are unclear. The ... In contrast to migraine, comorbidity of typical migraine aura does not appear to worsen symptoms. ...
This is in contrast to type 1 diabetes in which there is an absolute insulin deficiency due to destruction of islet cells in ... Aerobic exercise leads to a decrease in HbA1c and improved insulin sensitivity.[94] Resistance training is also useful and the ... This may be due to enhanced sensitivity to a Western lifestyle in certain ethnic groups.[127] Traditionally considered a ... "Human gut microbes impact host serum metabolome and insulin sensitivity". Nature. 535 (7612): 376-81. Bibcode:2016Natur.535.. ...
In contrast, prices in the US and the UK have recently skyrocketed, then fallen as a result of changes in supply and storage.[ ... Due to the sensitivity of liquefaction facilities to sulfur and mercury elements, the gas being sent to the liquefaction ...
In contrast, other approaches may be partially recognized and others have no regulation at all.[152] In some cases, promotion ... sensitivity to giving equal measure to beliefs and practices of other cultures (cultural relativism), and growing frustration ... Traditional medicine refers to the pre-scientific practices of a certain culture, in contrast to what is typically practiced in ... In addition, in most countries, alternative therapies (in contrast to pharmaceuticals) can be marketed without any proof of ...
... 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 ...
By contrast, humans and other primates accumulate the virus throughout their body and specifically in their blood, but not very ... such as light sensitivity, excess tearing, and vision loss have been described.[142] ...
... in contrast to high performers, "poor performers do not learn from feedback suggesting a need to improve".[11] ... emotional sensitivity toward other people and their perceptions of other people.[9] ...
Generally speaking, retinoids increase the skin's sensitivity to sunlight and are therefore recommended for use at night.[1] ... In contrast, if the microcomedone occurs deep within the hair follicle, this causes the formation of a whitehead (known as a ... The procedure is painful and has many potential side effects such as skin sensitivity to sunlight, redness, and decreased ...
In contrast, conjunctivitis secondary to infection with chlamydia (Chlamydia trachomatis) produces conjunctivitis after day ... Curative treatment as a rule, conjunctival cytology samples and culture sensitivity swabs should be taken before starting ...
Most work suggests that the peak spectral sensitivity of the receptor is between 460 and 482 nm. Steven Lockley et al. in 2003 ... This complexity becomes both important and necessary for detecting color, contrast, edges, etc. ... The photoreceptor proteins in the three types of cones differ in their sensitivity to photons of different wavelengths (see ... with peak spectral sensitivities to environmental and experimental light matching that for the melanopsin photopigment. Their ...
In contrast to the trend of decreasing electronegativities and ionisation energies of the alkali metals, francium's ... to make a large enough target to increase the sensitivity of the experiment to the required level; einsteinium has not been ...
However, the sensitivity of the DRE for injuries of the spinal cord, pelvis, and bowel is poor, and false positive and negative ... Double-contrast barium enema. *Endoanal ultrasound. *Enteroclysis. *Lower gastrointestinal series. *Small-bowel follow-through ... is not an adequate screen due to low sensitivity for advanced tumor and colorectal cancer.[20] Screening for colon cancer this ...
In contrast, the whaling industry, with the moratorium in place, generates US$31 million (UK£20 million) per year.[96] The size ... "Quantifying the sensitivity of Arctic marine mammals to climate-induced habitat change" (PDF). Ecological Applications. 18 (2 ...
scattering, has a relative sensitivity to ν. e. {\displaystyle \nu _{e}}. s and heavy-flavor neutrinos of ∼7:1.[15] Since the ... Highly relativistic muons, in contrast, travel almost straight through the detector and produce rings with sharp edges. ... Higher sensitivity was also necessary to obtain high statistical confidence in its results. This led to the construction of ...
Erogenous sensitivity is measured by the capabilities to reach orgasms in genital sexual activities, like masturbation and ... the latter is named in contrast to top surgery, which is surgery to the breasts; bottom surgery does not refer to surgery on ... However, these are counted upon the procedures and surgical tricks which are used to preserve the sensitivity. Considering the ... Selvaggi, G., Monstrey, S., Ceulemans, P., T'Sjoen, G., De Cuypere, G., & Hoebeke, P. (2007). "Genital sensitivity after sex ...
In contrast to fresh pasta, dried pasta needs to be dried at a low temperature for several days to evaporate all the moisture ... To address needs of people affected by gluten-related disorders (such as coeliac disease, non-celiac gluten sensitivity and ... Gluten-related disorders such as coeliac disease, wheat allergy and noncoeliac gluten sensitivity are increasingly being ...
In healthy people moclobemide has a relatively small suppressing effect on REM sleep; in contrast, depressed people who have ... Korn A, Wagner B, Moritz E, Dingemanse J (1996). "Tyramine pressor sensitivity in healthy subjects during combined treatment ... There is no need for dietary restrictions in contrast to people on irreversible MAOIs and apart from an important interaction ... in contrast to irreversible MAOIs.[9] However, some rare cheeses that have a high tyramine level may possibly cause a pressor ...
In contrast, beta-adducin is expressed at high levels in brain and hematopoietic tissues. Adducin binds with high affinity to ... 1997). "Polymorphisms of alpha-adducin and salt sensitivity in patients with essential hypertension". Lancet. 349 (9062): 1353- ...
"Laser in situ keratomileusis for myopia and the contrast sensitivity function."। Journal of cataract and refractive surgery 30 ...
939 In contrast mature sperm cells largely use protamines to package their genomic DNA, most likely because this allows them to ... can recognise lysine methylation with exquisite sensitivity and differentiate mono, di and tri-methyl lysine, to the extent ...
In contrast, conjunctivitis secondary to infection with C. trachomatis produces conjunctivitis 3 days to 2 weeks after delivery ... Curative treatment as a rule, conjunctival cytology samples and culture sensitivity swabs should be taken before starting ...
By contrast, black and mixed race Brazilians earned on average 58% as much as whites in 2014.[170] The gap in income between ... his sensitivity in other respects to black concerns kept civil rights leaders from any serious break" with Clinton, who enjoyed ... In contrast to the US, during the slavery period and after, the Portuguese colonial government in Brazil and the later ... By contrast, slave records from Louisiana show that the French and Spanish colonists recorded more complete identities of the ...
In contrast to the accepted Occupation Theory, Rate Theory proposes that the activation of receptors is directly proportional ... the number of receptors to a given hormone or neurotransmitter to alter their sensitivity to different molecule. This is a ...
Two or more positive criteria have a sensitivity of 88.2% and a specificity of 92.0% of describing GPA.[13][18] ... In contrast, administering pulsed doses of intravenous cyclophosphamide is equally effective for inducing remission, results in ...
This can be contrasted with paracrine signaling, intracrine signaling, or classical endocrine signaling. An example of an ... "Neuregulin-1-Mediated Autocrine Signaling Underlies Sensitivity to HER2 Kinase Inhibitors in a Subset of Human Cancers". Cancer ...
In contrast with nets, which are usually used in subsistence and commercial fishing, fishing rods are more often used in ... This influences not only the casting and the fish-fighting properties, but also the sensitivity to strikes when fishing lures, ... Some fishermen do feel a difference in sensitivity with two-piece rods, but most do not. ... being the more prized rods due to their increased sensitivity to fish bites and the heavier feel that helps balance the rods. ...
In contrast, theories of the origin of the primordial state remain very speculative. If one extrapolates the Lambda-CDM model ... "Animation: Matter Content Sensitivity. The matter-radiation ratio is raised while keeping all other parameters fixed" ...
"Dipeptidyl-peptidase-like-proteins confer high sensitivity to the scorpion toxin AmmTX3 to Kv4-mediated A-type K+ channels" ... in contrast to Aa1 and BmTX3.[1][2][4] ...
In contrast, social identity theory posits a psychological drive for positively distinct social identities as the general root ... evolution may have favoured a greater sensitivity in males in situations which resulted in an advantageous payoff for their in- ...
Webb edited by Henrik S. Thomsen, Judith A. W. (2014)։ Contrast media : safety issues and ESUR guidelines. (Third ed.)։ ... Management options for patients with aspirin and nonsteroidal antiinflammatory drug sensitivity»։ The Annals of pharmacotherapy ...
Chromatic contrast refers to the occurrence of differences in chromaticity (saturated, hue-full color) in a visual percept ( ... chromatic contrast sensitivity is higher than achromatic contrast sensitivity when measured as cone contrasts. This is the case ... While sensitivity for luminance contrast decreases during smooth pursuit, sensitivity for isoluminant L-M and S-(L+M) contrast ... Chromatic spatial contrast sensitivity functions are low-pass [7]. This means that contrast sensitivity declines with high ...
Contrast sensitivity in organic-solvent-induced chronic toxic encephalopathy. Bibliographic information. Dec. 1995, Vol.37, No. ...
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 ...
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 ...
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 ...
Retinal receptive fields and systems of P cell and M cell neurons are involved in contrast perception. P cells are... ... contrast denotes the relationship between the luminance of an object and its immediate background. ... contrast sensitivity testing is a more sensitive measure of visual function. Contrast sensitivity is also a sensitive tool to ... decreased contrast sensitivity and spatial localization. The aim of this report is to show how contrast sensitivity testing can ...
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 ...
Spatial contrast sensitivity functions (CSFs) were measured for 3 tree shrews. Our two-alternative forced-choice discrimination ... Spatial Contrast Sensitivity of the Tree Shrew Vision Res. 1984;24(9):1037-42. doi: 10.1016/0042-6989(84)90080-4. ... Spatial contrast sensitivity functions (CSFs) were measured for 3 tree shrews. Our two-alternative forced-choice discrimination ... In general, the CSFs were of the typical band-pass type with peak sensitivity occurring at approximately 0.7 c/deg. Estimates ...
... 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 ...
... 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 ...
VEP CRFs in infants were found to have a form similar to those observed in adults, being linear functions of log contrast over ... Contrast response functions (CRFs) for the VEP were obtained with a Discrete Fourier Transform (DFT) technique employing swept ... Measurement of spatial contrast sensitivity with the swept contrast VEP Vision Res. 1989;29(5):627-37. doi: 10.1016/0042-6989( ... being linear functions of log contrast over a range of near-threshold contrasts. CRFs with low and high contrast lobes were ...
... contrast sensitivity include A Laser-induced Mouse Model of Chronic Ocular Hypertension to Characterize Visual Defects, ...
Decreased contrast sensitivity at high altitude Katrin Gekeler, Andreas Schatz, Manuel Dominik Fischer, Kai Schommer, Katrin ...
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 ...
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.. ...
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 ...
These results are consistent with the previous work showing enhanced contrast sensitivity in migraine-with-aura for small, ... Overall, contrast thresholds for the migraine group were lower than those in the control group. There was no difference in the ... In separate blocks of trials, the target was presented alone or was flanked by two additional collinear, high contrast Gabors. ... Observers indicated which of two intervals contained a centrally presented, vertical Gabor target of varying contrast. ...
... 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 ...
... 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 ...
... 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. ...
... discusses the findings of his study comparing reliability of testing methodologies for visual acuity and contrast sensitivity ... Visual acuity and contrast sensitivity are among the most common measures of visual abilities and a battery of tests exists to ... So, we chose a battery of tests, a group of tests, certain contrast sensitivity testing and certain visual acuity testing. ... MD Mag: What did you find when comparing testing methodology for measuring visual acuity and contrast sensitivity? ...
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. ...
If you dont want to take the risk of having lasik surgery, yellow tinted lens can help offset low contrast sensitivity. ... There are several options for people with low contrast sensitivity. Custom LASIK surgery, Yellow filtered lenses and ... What are the remedy for low contrast sensitivity?. Is there any home remedy for low contrast sensitivity? I dont want to have ... If low contrast sensitivity is caused by higher-order aberrations, wavefront lenses or LASIK is the right choice. Another ...
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 ...
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 ...
contrast sensitivity for low-spatial-frequency stimuli in first-episode schizophrenia can be successfully modeled as a function ... contrast sensitivity and. broadened orientation tuning in chronic schizophrenia can be successfully modeled by a combination of ... Computational Modeling of Contrast Sensitivity and Orientation Tuning in First-Episode and Chronic Schizophrenia ...
London UK - Contrast Sensitivity Course. Posted on November 13, 2014. At the recent ESCRS meeting in London, Dr David Evans ... Contrast Sensitivity Detects Vision Problem in Genetic Disorder * CSV-1000 Shows Tinted Lenses Improve Vision for Diabetic ... During the course, Dr Evans covered the scientific basis of testing contrast sensitivity with sine-wave gratings and how it ... Dr Pamel provided detailed information about the clinical significance of contrast sensitivity testing for cataract ...
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 ...
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 ...
Dynamic Vision Sensors (DVS) have recently appeared as a new paradigm for vision sensing and processing. They feature unique characteristics such as contra
  • and the relationship between chromatic contrast sensitivity, spatial resolution, and chromatic acuity. (springer.com)
  • The authors explain that testing the peak of contrast sensitivity function provides a useful clinical adjunct to standard visual acuity assessments. (aao.org)
  • Even if you have 20/20 visual acuity , you can have eye or health conditions that may diminish your contrast sensitivity and make you feel that you are not seeing well. (allaboutvision.com)
  • A person with normal visual acuity but poor contrast sensitivity might see the trees in the foreground clearly (high contrast), but have trouble seeing the contours of the mountains against the sky in the background (low contrast). (allaboutvision.com)
  • In most cases, people with cataracts notice a significant improvement in both visual acuity and contrast sensitivity after cataract surgery. (allaboutvision.com)
  • If your eye doctor determines that you need a contrast sensitivity test, it likely will be administered after a standard visual acuity test and before your pupils are dilated . (allaboutvision.com)
  • In amblyopia, considering developmental defect of spatial visual processing in the central nervous system, the main features are decreased recognition, Vernier and grating acuity, decreased contrast sensitivity and spatial localization. (srce.hr)
  • In our patients with different types of amblyopia and refractive errors we performed contrast sensitivity testing and comparison with visual acuity assessed by standard Snellen charts. (srce.hr)
  • In comparison with standard Snellen visual acuity, contrast sensitivity testing is a more sensitive measure of visual function. (srce.hr)
  • Contrast sensitivity is also a sensitive tool to detect suppression even in patients with normal or near normal visual acuity. (srce.hr)
  • The measurement of the contrast sensitivity of the eye is a more complete assessment of vision than standard visual acuity measurement. (thefreedictionary.com)
  • The correlations of neuroticism with near visual acuity, distance visual acuity, and contrast sensitivity were all not significant ([less than or equal to] 0. (thefreedictionary.com)
  • 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)
  • We start by measuring each athlete's visual acuity, eye-hand coordination, contrast sensitivity and reaction time to assess how well an athlete sees and then provide a game plan to address areas of improvement. (thefreedictionary.com)
  • The CSF therefore provides a much more complete description of visual sensitivity and more subtle deficits than those identified by acuity tests can be demonstrated (cf. (druglibrary.org)
  • It also provides a built-in measure of acuity, because a point is reached when a grating is so fine that it cannot be resolved, even at maximum contrast. (druglibrary.org)
  • Pinakin Davey, DO, PhD, discusses the findings of his study comparing reliability of testing methodologies for visual acuity and contrast sensitivity at ARVO 2019. (hcplive.com)
  • Visual acuity and contrast sensitivity are among the most common measures of visual abilities and a battery of tests exists to measure them. (hcplive.com)
  • Pinakin Davey, DO, PhD, professor and director of research at Western University, helped author a study presented at the 2019 Annual Meeting of the Association for Research in Vision and Ophthalmology that explored the reliability of testing methodologies for measuring visual acuity and contrast sensitivity. (hcplive.com)
  • MD Mag: What did you find when comparing testing methodology for measuring visual acuity and contrast sensitivity? (hcplive.com)
  • So, we chose a battery of tests, a group of tests, certain contrast sensitivity testing and certain visual acuity testing. (hcplive.com)
  • On the other hand, the contrast sensitivity function (CSF) generally takes longer to assess than visual acuity, but it is better correlated with improvement in a range of visual tasks and, notably, with improvements in binocular vision. (frontiersin.org)
  • We conclude that monocular and binocular contrast sensitivity deficits define important characteristics of amblyopia and strabismus that are not captured by visual acuity alone and can be measured efficiently using the quick CSF. (frontiersin.org)
  • During the course, Dr Evans covered the scientific basis of testing contrast sensitivity with sine-wave gratings and how it compares to standard visual acuity as a measure for real-world vision. (vectorvision.com)
  • Contrast sensitivity and visual acuity were measured by optotype figures at full contrast, 2.5% contrast, and 0.6% contrast. (ebscohost.com)
  • Corrected Super Vision Test (Precision Vision, La Salle, IL) high contrast and small letter contrast sensitivity, uncorrected postoperative contrast sensitivity function, and uncorrected and corrected distance visual acuity were measured preoperatively and at 1, 3, 6, and 12 months postoperatively. (healio.com)
  • Clinical vision testing usually focuses on visual acuity using high contrast black and white tests. (healio.com)
  • London-In an intra-individual comparison of spheric and aspheric monofocal IOLs, significantly better contrast sensitivity was observed in eyes in which the aspheric lens had been implanted, but there was no difference in best-corrected visual acuity (BCVA), said Katrin Petermeier, MD, University Eye Hospital, Eberhard-Karls University, Tuebingen, Germany. (ophthalmologytimes.com)
  • Low-contrast visual acuity was assessed with Pelli-Robson charts. (ophthalmologytimes.com)
  • Photopic and mesopic contrast sensitivity were measured by functional acuity contrast tests using the Ginsburg Box. (ophthalmologytimes.com)
  • The difference in BCVA, low-contrast visual acuity, and residual refractive error between lenses was not statistically significant. (ophthalmologytimes.com)
  • It has been demonstrated that perceptual learning (PL) can modulate these low-level lateral interactions, resulting in improved visual acuity and contr ast sensitivity. (iospress.com)
  • 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 pre- and post-learning tasks included lateral interactions at different target-to-flankers separations (i.e., 2, 3, 4, 8λ) and included a range of spatial frequencies and stimulus durations as well as visual acuity, Vernier acuity, contrast-sensitivity function, and foveal crowding. (iospress.com)
  • 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)
  • Follow-ups after 5-7 months showed not only complete maintenance of PL effects on visual acuity and contrast sensitivity function but also further improvement in these tasks. (iospress.com)
  • Contrast sensitivity was found to be better than visual acuity for predicting a pilot's ability to detect a small, semi-isolated, air-to-ground target. (semanticscholar.org)
  • Eleven instructor pilots had their acuity measured by both conventional and contrast sensitivity methods. (semanticscholar.org)
  • Conventionally determined visual acuity proved to be a poor predictor of a pilot's ability to detect a small low contrast target. (semanticscholar.org)
  • Contrast sensitivity measured by two different test methods in healthy, young adults with normal visual acuity. (semanticscholar.org)
  • By comparing our results with acuity values derived from anatomical estimates of ganglion cells' density, we conclude that the optokinetic 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. (arvojournals.org)
  • Purpose: To investigate the effects of the transmittance of diffusive blurson visual acuity and contrast sensitivity. (koreascience.or.kr)
  • Visual acuity and contrast sensitivity were measured with varying the transmittance of diffusive blur in order to simulate progression of cataract and concentration in fog. (koreascience.or.kr)
  • Conclusions: The transmittance of diffusive blur causes a reduction in visual acuity and contrast sensitivity, a deviation of normal range of contrast sensitivity, and a shift of peak contrast sensitivity. (koreascience.or.kr)
  • Effects of Induced dioptric blur on visual acuity and contrast sensitivity. (koreascience.or.kr)
  • Purpose: To evaluate computerized methods for measuring glare sensitivity and visual acuity at 3 contrast levels in cataract patients. (diva-portal.org)
  • Measured were glare sensitivity and visual acuity at 3 contrast levels using the Ophthimus Y-VA Contrast Sensitivity lest and Glare Test. (diva-portal.org)
  • Correlation coefficients between preoperative visual acuity and contrast sensitivity at 90%, 25%, and 10% were 0.50 (P = .01), 0.53 (P = .006), and 0.45 (P = .02), respectively, and between preoperative visual acuity and preoperative glare difference, 0.45 (P = .02). (diva-portal.org)
  • A significant correlation was found between age and visual acuity in the control group at all contrast levels: 90% (r = 0.61, P = .0018 ), 25% (r = 0.52, P = .01), and 10% (r = 0.42, P = .04). (diva-portal.org)
  • This review paper is a discussion of the development of visual acuity and contrast sensitivity into childhood. (journalofoptometry.org)
  • The literature on subjective (measured with preferential looking or psychophysical methods) and objective (visually-evoked potential) measures of visual acuity and contrast sensitivity was examined with particular emphasis on studies of children over the age of 5 years and those articles that compared different age groups and those that made a comparison with adults. (journalofoptometry.org)
  • Visual acuity was found to be fully mature between the ages of 5 and the mid teenage years, while contrast sensitivity was found to mature fully between the ages of 8 to 19 years. (journalofoptometry.org)
  • Visual acuity at three contrasts and two brightnesses, and critical flicker frequency (CFF) at two brightnesses, were measured morning and evening on 24 subjects for five successive days. (osapublishing.org)
  • There are some pathological conditions that reduce contrast sensitivity without impairing visual acuity, and the test will help in the identification of these conditions. (omtao.in)
  • However, reduced contrast sensitivity and reduced visual acuity often occur together, so that some (by no means all) children with visual impairment also have reduced contrast sensitivity. (omtao.in)
  • A child with an equivalent acuity but with reduced contrast sensitivity has a much more severe impairment, and will not get the same benefit from enlargement. (omtao.in)
  • Treatment for visual deficits (including amblyopia therapies) can result in improved contrast sensitivity sometimes in the absence of increased visual acuity. (omtao.in)
  • Some progressive eye conditions will result in changes in contrast sensitivity, so that monitoring contrast sensitivity alongside visual acuity (and other visual functions) may be essential in determining progress of the condition. (omtao.in)
  • Like its 'sister' test, the Cardiff Acuity Test, the Cardiff Contrast Test uses vanishing Optotypes. (omtao.in)
  • Testing is identical to the measurement of visual acuity at high contrast level. (leatest.com)
  • Now it's easy to measure, record and detect changes in the transfer of visual information when the change only affects visual acuity at low contrast levels. (leatest.com)
  • Test for quick measurement of low contrast visual acuity at 25%, 10%, 5%, 2.5%, and 1.25% contrast by measuring the distance where the symbols are seen. (leatest.com)
  • Contralateral healthy eyes comprised the control group.LogMAR best corrected visual acuity and contrast sensitivity at four spatial frequencies - 3, 6, 12 and 18 cycles/degree - were measured before and after surgery for macula-on RDD. (linkoph.com)
  • Not only can a carefully selected option address the glare, it can also lead to functional improvements in my patients' visual performance in terms of acuity, contrast sensitivity , and improved mobility. (thefreedictionary.com)
  • The goal of this study was to predict visual acuity (VA) and contrast sensitivity function (CSF)with tissue redness grading after pterygium surgery. (iium.edu.my)
  • The Visual Contrast Sensitivity (VCS) test is a CONTRAST test, not an acuity test. (drlarsen.com)
  • EN]Purpose: To introduce a new application (ClinicCSF) to measure Contrast Sensitivity Function (CSF) with tablet devices, and to compare it against the Functional Acuity Contrast Test (FACT). (upv.es)
  • ES] Objetivo: Introducir una nueva aplicación (ClinicCSF) para medir la Función de Sensibilidad al Contraste (FSC) con dispositivos de tableta, y compararla con el test Functional Acuity Contrast Test (FACT). (upv.es)
  • Postoperative visual acuity (VA), refraction, and contrast sensitivity (with and without glare) tests were done at 1 and 3 months. (irjo.org)
  • Visual acuity (VA) and contrast sensitivity (CS) characterize different aspects of visual function. (umn.edu)
  • There is greater variability in color vision and contrast acuity in AMD patients. (kingdevicktest.com)
  • By combining the information received in each eye, binocular summation can improve visual acuity, contrast sensitivity, flicker perception, and brightness perception. (wikipedia.org)
  • Abstract- Contrast sensitivity was measured in pseudophakic and aphakic patients. (edu.hk)
  • Contrast sensitivity is a very important measure of visual function, especially in situations of low light, fog or glare, when the contrast between objects and their background often is reduced. (allaboutvision.com)
  • mesopic contrast sensitivity also was measured with glare (35 lux). (ophthalmologytimes.com)
  • To assess contrast sensitivity (CS) both with and without the presence of glare, in patients implanted bilaterally with light-adjustable intraocular lenses (LALs).Patients were treated to have one eye set to emmetropia and the contralateral with induced negative spherical aberration (SA) to increase the depth of focus. (arvojournals.org)
  • There were not significant differences between the binocular contrast sensitivity measured with and without glare. (arvojournals.org)
  • Measuring contrast sensitivity in normal subjects with OPTEC 6500: influence of age and glare. (koreascience.or.kr)
  • Postoperatively, median values were similar to those in the age-matched control group in all parameters except glare sensitivity, which was significantly higher in the pseudophakic group (P = .03). (diva-portal.org)
  • But the outcome was surprisingly suboptimal in the form of post-op refractive surprises, spectacle dependency, reduced reading speed, reduced level of contrast sensitivity and most alarmingly the photic phenomena (Halos, Glare, Starburst etc. (thefreedictionary.com)
  • Visual performance is strongly impacted by contrast sensitivity, glare and dark adaptation, Stringham said. (healio.com)
  • Glare and contrast sensitivity are affected by both external and internal variables, with internal referring to inner-eye changes over time, such as cataracts. (healio.com)
  • At 3 months after surgery, contrast sensitivity with and without glare showed statistically significant inter-group differences at 6, 12 and 18 cycles per degree (CPD), and at 6 and 12 CPD, respectively. (irjo.org)
  • 4. In twenty-one X-cells the relation between the contrast and spatial frequency of drifting sinusoidal gratings which evoked the same small response was measured. (nih.gov)
  • Contrast response functions (CRFs) for the VEP were obtained with a Discrete Fourier Transform (DFT) technique employing swept contrast gratings. (nih.gov)
  • It provides an evaluation of the detection of objects (usually sinusoidal gratings) of varying spatial frequencies and of variable contrast and thus obtaining a contrast sensitivity function (CSF). (thefreedictionary.com)
  • In the second study (3 females) the same spatial frequencies were used but the gratings were also contrast reversed at different temporal frequencies (in different sessions), providing us with a spatiotemporal sensitivity profile. (druglibrary.org)
  • Although there were individual differences, we found a small but significant reduction in contrast sensitivity at all spatial frequencies for stationary gratings. (druglibrary.org)
  • However, at lower spatial frequencies, eye movements were elicited by low contrast gratings, 1.3 % and 2.9% contrast in H . portusjacksoni and C. punctatum respectively. (biologists.org)
  • Contrast sensitivity functions derived for 2-degree sinusoidal gratings at a luminance of 45 cd/m 2 for red (625 nm), green (525 nm), and blue (475 nm) LEDs. (rpi.edu)
  • Contrast sensitivity functions derived for 2-degree sinusoidal gratings at typical luminance values (red: 125 cd/m 2 , green: 35 cd/m 2 , blue: 5 cd/m 2 ) for red (625 nm), green (525 nm), and blue (475 nm) LEDs. (rpi.edu)
  • The gratings varied in contrast and spatial frequency, and could be switched out during the experiment. (rpi.edu)
  • A method and apparatus for objectively determining the visual contrast sensitivity function of a human subject involves subjecting the vision of the human subject to a plurality of sine wave gratings differing in spatial frequency and contrast levels. (google.com)
  • Compared with measures made using CRT generated square wave gratings of variable contrast and spatial frequency they were also shown to provide a valid measure of CSF in the mid to high spatial frequency range. (auckland.ac.nz)
  • The Pelli Robson contrast sensitivity chart tests your ability to detect letters that are gradually less contrasted with the white background as your eyes move down the chart. (allaboutvision.com)
  • Probably the most widely used device to test contrast sensitivity is the Pelli Robson contrast sensitivity chart. (allaboutvision.com)
  • Contrast sensitivity was measured using the Pelli-Robson Chart and the CSV1000E test. (hindawi.com)
  • In 5 subjects with corrected-to-normal vision (ages ranging from 20 to 57), we tested contrast sensitivity weekly over a 4-8-week period with the novel quick CSF method (Lesmes et al, 2010) and established contrast sensitivity charts (Pelli-Robson and Vistech). (arvojournals.org)
  • Results from the test are presented in a manner that is consistent with scoring of the Pelli-Robson Contrast Test for adults. (omtao.in)
  • Continued improvement was also observed in contrast sensitivity as determined by Pelli-Robson low-contrast testing. (thefreedictionary.com)
  • They say that an ideal contrast sensitivity test would evaluate peak contrast sensitivity function, be reliable and not be influenced by language ability. (aao.org)
  • Detailed contrast sensitivity measurements that include both size (spatial frequency) and contrast are used to plot a person's contrast sensitivity function (CSF). (allaboutvision.com)
  • In every case it was found that the reciprocal of this relation, the contrast sensitivity function, could be satisfactorily described by the difference of two Gaussian functions. (nih.gov)
  • 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 receptive field centre was determined and found to be consistent with the cell's measured contrast sensitivity function. (nih.gov)
  • 7. Reducing the retinal illumination produced changes in the contrast sensitivity function of an X-cell which suggested that the diameters of the summating regions of the receptive field increased while the surround region became relatively ineffective. (nih.gov)
  • The two-dimensional Fourier amplitude spectrum of the field is multiplied by the contrast sensitivity function of the eye to generate the internal representation which visual psychophysicists believe is the basis for the human percept. (nist.gov)
  • Multiplying the Fourier amplitude spectrum of the test pattern in Figure 10 by the contrast sensitivity function in Figure 11 and computing the inverse Fourier transform of the result gives the perceived field shown in Figure 12 . (nist.gov)
  • RESULTS: After a preliminary theoretical study on the effect of frequency selective and overall reductions in the contrast sensitivity function of a single mechanism, we present cases of real subjects with glaucoma and diabetes, suffering alterations of different magnitude in the three mechanisms. (biomedsearch.com)
  • By measuring threshold at several different spatial frequencies (defined as the number of cycles of dark and light bars per degree of visual angle), a contrast sensitivity function (CSF) may be constructed. (druglibrary.org)
  • To compare contrast sensitivity, acquired color vision deficiency, and reading ability in patients with glaucoma at different stages of the disease and to establish correlations between visual field parameters and visual function scores. (hindawi.com)
  • 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)
  • The contrast sensitivity function (CSF) provides a useful functional endpoint for development of ophthalmic drugs and devices. (arvojournals.org)
  • The area under the logarithm of contrast sensitivity function did not differ significantly over time ( P = .09) or between groups ( P = .16). (healio.com)
  • Wavefront-guided and wavefront-optimized PRK and LASIK procedures maintained high contrast, small letter contrast sensitivity, and contrast sensitivity function 12 months postoperatively. (healio.com)
  • has an advantage over typical vision testing: it can be used to describe the threshold of visual quality and to generate contrast sensitivity function (CSF). (healio.com)
  • But to be able to employ such a technique to colored beams generated by LED systems, it necessary to have corresponding contrast sensitivity functions (CSFs), which describe the contrast sensitivity of the visual system as a function of spatial frequencies. (rpi.edu)
  • This property can be robustly estimated by measuring the contrast sensitivity as a function of different spatial frequencies, defined as the number of achromatic vertical bright and dark stripe pairs within one degree of visual angle. (arvojournals.org)
  • This contrast sensitivity function (CSF) has been estimated for different animal groups, but data on fish are limited to two free-swimming, freshwater species (i.e., goldfish and bluegill sunfish). (arvojournals.org)
  • This approach is more comprehensive than measuring maximum spatial resolution only (Lind & Kelber, 2011 ), as it expresses contrast sensitivity as a function of spatial frequency (number of vertical bright and dark stripe pairs within one degree of visual angle). (arvojournals.org)
  • From an intersection point of contrast sensitivity function, we could calculated the transmittance of the diffusive blur being off the normal range and the shift to peak spatial frequency. (koreascience.or.kr)
  • The peak of contrast sensitivity function was observed to move from 6 to 3 cpd at transmittance of about 78.70%, the contrast sensitivities for all frequencies at transmittance of about 69.71% were deviated from the normal range. (koreascience.or.kr)
  • Behavioural determination of the contrast sensitivity function of the eagle Aquila audax. (semanticscholar.org)
  • article{Reymond1981BehaviouralDO, title={Behavioural determination of the contrast sensitivity function of the eagle Aquila audax. (semanticscholar.org)
  • A set of near Bailey-Lovie logMAR letter charts that varied in contrast from 0.40 dB (C = 0.95) to 58.0 dB (C=0.001) were used to measure the middle and high spatial frequency range of the contrast sensitivity function (CSF) of 15 subjects with age-related maculopathy (ARM) and 15 age-matched normal subjects. (auckland.ac.nz)
  • Both the shape and sensitivity of the contrast response functions varied as a function of visual area, eccentricity and temporal frequency. (arvojournals.org)
  • The human contrast sensitivity function (CSF) has also been studied extensively as a predictor of visual performance under real-world conditions. (vt.edu)
  • Contrast sensitivity (CS) testing is an important measure of visual function reflecting variations in everyday visual experience in different conditions and helps to identify more subtle vision loss. (arvojournals.org)
  • Contrast sensitivity (CS), an important measure of visual function, is the ability to detect a difference between the luminance of an object and its background. (arvojournals.org)
  • Contrast perception is an important visual function. (springer.com)
  • Contrast sensitivity provides a way of assessing visual function that is more sensitive than conventional targets. (tryunity.net)
  • It has been demonstrated that the contrast sensitivity function of AMD patients is similar in shape to the normal CSF, but it is shifted along the spatial frequency and the contrast sensitivity axes 5 . (psychophysics.uk)
  • Contrast sensitivity function and macular degeneration (redrawn from Chung and Legge, 2016). (psychophysics.uk)
  • Visual sensitivity is comprehensively described by the Contrast Sensitivity Function (CSF), but current routine clinical care does not include its assessment because of the time-consuming need to estimate thresholds for a large number of spatial frequencies. (adaptivesensorytech.com)
  • The spectral response of S-cones peak at 420 nm, M-cones at 534 nm, and L-cones at 564 nm, with significant overlap in their spectral response ranges and varying degrees of sensitivity at these range of wavelengths specified by the function m k (λ), k = r, g, b, as depicted in Figure 2.1(a) . (informit.com)
  • where m k (λ) is the wavelength sensitivity function (also known as the color matching function) of the k th cone type or color sensor. (informit.com)
  • Both groups had significant improvements in contrast sensitivity at six cycles per degree (the primary outcome measure), in other measures of contrast sensitivity and visual function, and in the amount of macular pigment. (thefreedictionary.com)
  • f, Averaged sensitivity for detection of the patterns as a function of their probability, measured on three human subjects (different colors). (nih.gov)
  • The ability to detect contrast is part of the brain's function. (drlarsen.com)
  • Visual contrast sensitivity testing measures your ability to see details at low contrast levels and is often used as a nonspecific test of neurological function. (quantifiedbob.com)
  • cigarette and tobacco use may also affect contrast function at these spatial frequencies. (quantifiedbob.com)
  • What is the best luminance contrast weighting-function for image quality optimization? (westminster.ac.uk)
  • Agreement B. Contrast sensitivity from the new app (CSDC at 0D) and the contrast sensitivity function for frequencies of 3,6,12 and 18 cycles per degree. (benthamopen.com)
  • CSF test: Contrast sensitivity function measured for frequencies of 3 cfnd (a), 6 cfnd (b), 12 cfnd, (c) and 18 cfnd (d). (benthamopen.com)
  • There are numerous variants of the LEA test which can be used to assess the visual capabilities of near vision and distance vision, as well as several other aspects of occupational health, such as contrast sensitivity, visual field, color vision, visual adaptation, motion perception, and ocular function and accommodation (eye). (wikipedia.org)
  • The deficit in contrast sensitivity in anisometropic amblyopia was most pronounced at high spatial frequencies. (srce.hr)
  • Contrast sensitivity in strabismic amblyopia may be normal or abnormal at high frequencies. (srce.hr)
  • Spatial frequencies tested ranged from 0.1 to 2.0 c/deg and grating contrast was varied trial-by-trial using a modified staircase technique. (nih.gov)
  • 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)
  • 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)
  • Intra-individual comparison showed 20% higher contrast sensitivity for the [aspheric lens] at all spatial frequencies tested and under all three illumination states,' she explained. (ophthalmologytimes.com)
  • Contrast sensitivity was decreased in all spatial frequencies. (koreascience.or.kr)
  • At 20cd/m2 the shapes of the CSFs are similar: both species show a peak in sensitivity with attenuation of higher and lower spatial frequencies. (semanticscholar.org)
  • A loss of contrast at high spatial frequencies due to retinal "smear" may be the cause of this increase in high spatial frequency thresholds under vibration. (vt.edu)
  • Tests that measure the sensitivity to contrast at different spatial frequencies provide more information about the functionality of the photoreceptors and their postreceptoral pathways. (psychophysics.uk)
  • This demonstrates the benefit of assessment of the whole CSF compared to sensitivity at individual spatial frequencies only. (adaptivesensorytech.com)
  • The gray line represents the contrast sensitivity curve (average, both eyes) over the tested range of spatial frequencies among healthy research subjects as published by Dr. Shoemaker, and the red line is the curve formed by the highest level of contrast you were able to see in this test. (quantifiedbob.com)
  • In contrast, our approach utilizes high-sensitivity visual characteristics based on the assumption that the higher contrast sensitivity of spatio-temporal frequencies will correlate more effectively with shorter perception times. (sae.org)
  • We show that maximal quality for our test images, results from cCSFs and cVPFs, mutated to boost contrast in the higher visible frequencies. (westminster.ac.uk)
  • Human participants were asked to perform a reaching movement toward a display and judge the orientation of a Gabor patch, near contrast threshold, briefly presented at random times before and during the reaching movement. (jneurosci.org)
  • VEP CRFs in infants were found to have a form similar to those observed in adults, being linear functions of log contrast over a range of near-threshold contrasts. (nih.gov)
  • Table S1 Relationship between contrast sensitivity and contrast threshold (contrast sensitivity = 1/contrast threshold). (thefreedictionary.com)
  • Contrast sensitivity defines the threshold between the visible and invisible, which has obvious significance for basic and clinical vision science. (adaptivesensorytech.com)
  • Fechner's 1860 review reported that threshold contrast is 1% for a remarkably wide range of targets and conditions. (adaptivesensorytech.com)
  • Mark Roark, OD, who practices in Indiana, presented information from his clinical research on contrast sensitivity threshold (CST) in patients taking carotenoid supplements. (healio.com)
  • We suggest contextual CSFs (cCSFs) and contextual discrimination functions (cVPFs) should provide bases for further improvement, since these are directly measured from pictorial scenes, modeling threshold and suprathreshold sensitivities within the context of complex masking information. (westminster.ac.uk)
  • Further testing is needed to determine what threshold of color and contrast best distinguishes AMD with the potential to detect AMD at an earlier stage and initiate more effective treatment. (kingdevicktest.com)
  • In its present form, the algorithm would serve to simulate alterations both in the spectral sensitivities and in the contrast sensitivities of the visual mechanisms. (biomedsearch.com)
  • While typical OCT images convey structural details of the sample, the contrast enhancement approach developed herein provides detailed angiography and spectral information from the sample. (octnews.org)
  • The reported LGNR molecular targeting methods, contrast sensitivity, spectral multiplexing, and high resolution comprise a promising approach for future OCT molecular imaging studies, which we call MOZART. (octnews.org)
  • 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)
  • Objectives: To determine whether blurred vision caused by exposure to triethylamine (TEA) can be detected by the measurement of contrast sensitivity. (ebscohost.com)
  • Cardiff Contrast Test is designed for low contrast measurement in toddlers and young children, and in older children or adults with intellectual impairment. (omtao.in)
  • So a measurement of contrast sensitivity can help determine appropriate management of a child's impairment. (omtao.in)
  • To explore the reliability of the Spaeth/Richman Contrast Sensitivity (SPARCS) test and to assess the contrast sensitivity (CS) distribution among subjects with various refractive errors. (ovid.com)
  • Spatial contrast sensitivity functions (CSFs) were measured for 3 tree shrews. (nih.gov)
  • In general, the CSFs were of the typical band-pass type with peak sensitivity occurring at approximately 0.7 c/deg. (nih.gov)
  • The results of behavioural experiments determining contrast sensitivity functions (CSFs) for the eagle Aquila audax and man at two low luminances are compared. (semanticscholar.org)
  • Traditionally measured contrast sensitivity functions (CSFs), have been often used as weighting-functions in image quality and difference metrics. (westminster.ac.uk)
  • Long-term exposure to low-level methylmercury in the riverside populations can lead to nervous system alterations, some of which are visual impairments such as loss of luminance contrast sensitivity, restricted visual fields and color vision defects. (readbyqxmd.com)
  • 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)
  • Age-related macular degeneration is a degenerative disorder of the macula which is characterised, in its early stages, by a partial sensitivity loss to contrast particularly at mesopic and scotopic light levels and a slower dark adaptation mechanism. (psychophysics.uk)
  • The Brain and Ocular Nutrition Conference's first day highlighted how macular carotenoids affect visual performance and contrast sensitivity. (healio.com)
  • The tablet-based K-D Variable Contrast Sensitivity Chart was used to measure color contrast sensitivity in patients with age-related macular degeneration (AMD). (kingdevicktest.com)
  • Thus, the possibility to perform high-sensitivity X-ray phase-contrast computed tomography with laboratory setups is of great interest for a broad range of high-resolution biomedical applications. (spie.org)
  • However, there are no direct behavioural measurements of spatial resolution or contrast sensitivity. (biologists.org)
  • Eye movements ceased at 0.38 cycles per degree, even for high contrasts, suggesting low spatial resolution. (biologists.org)
  • Our results suggest that vision in sharks is not 'poor' as previously suggested, but optimised for contrast detection rather than spatial resolution. (biologists.org)
  • This, in turn, is limited by the spatial resolution and contrast sensitivity of the underlying visual system. (biologists.org)
  • 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)
  • The term chromatic contrast is used in opposition to achromatic contrast , where differences only occur in luminance (gray level). (springer.com)
  • Achromatic contrast refers to differences in luminance, which are perceived as lightness differences. (springer.com)
  • Unlike achromatic contrast, chromatic contrast involves differences in chromaticity, which are differences along one or both of the chromatic dimensions as opposed to the achromatic dimension. (springer.com)
  • Images perceived after chromatic or achromatic contrast sensitivity losses. (biomedsearch.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)
  • The new lens offers an enhanced aspheric optic that improves image quality and increases contrast sensitivity in cataract surgery patients with astigmatism. (thefreedictionary.com)
  • Correction of ocular chromatic aberrations, in addition, also demonstrated improvement in the overall optical quality following cataract surgery by reducing blur and contrast vision [ 8 - 10 ]. (hindawi.com)
  • This article reviews the importance of contrast sensitivity to vision and its role in identifying many ocular diseases, and compares the strengths and weaknesses of contrast sensitivity testing methods. (aao.org)
  • For their latest study, van Elst's group sought to confirm their previous findings using objective methods, and to determine if any observed changes in the contrast sensitivity of depressed patients are due to changes in the eye or brain. (scienceblogs.com)
  • Methods:Amblyopic observers were trained on a contrast-detection task for a central target (i.e., a Gabor patch) flanked above and below by two high-contrast Gabor patches. (iospress.com)
  • However, the perception of contrast strongly depends on the transition between the two chromaticities. (springer.com)
  • Retinal receptive fields and systems of P cell and M cell neurons are involved in contrast perception. (srce.hr)
  • Last year, neuropsychiatrist Ludger Tebartz van Elst of the University of Freiburg and his colleagues reported that patients with MDD exhibited a reduced sensitivity to contrast, while a team of researchers from Yale showed that visual motion perception is enhanced in depression. (scienceblogs.com)
  • Here we assess concurrent changes in visual performance and perceived contrast before saccades, and show that saccade preparation enhances perception rapidly, altering early visual processing in a manner akin to increasing the physical contrast of the visual input. (jneurosci.org)
  • We presented pairs of associated images and pairs of non-associated images and compared their corresponding effect on subsequent performance in three different visual perception paradigms: contrast-sensitivity, global vs. local perception, and critical-flicker-fusion. (nature.com)
  • Problems can include trouble with contrast sensitivity , which is the ability to distinguish between objects of similar tone (e.g., milk in a white cup), and difficulty with depth perception (e.g., uncertainty of step height). (thefreedictionary.com)
  • Background:Amblyopic observers present abnormal spatial interactions between a low-contrast sinusoidal target and high-contrast collinear flankers. (iospress.com)
  • You can also turn each chart 90 degrees to assess any effects on vertical versus horizontal contrast sensitivity sinusoidal waveforms. (tryunity.net)
  • However, achieving high sensitivity with laboratory gbPC-CT setups still poses a challenge because several factors such as the reduced flux, the polychromaticity of the spectrum, and the limited coherence of the X-ray source reduce the performance of laboratory gbPC-CT in comparison to gbPC-CT at synchrotron facilities. (kit.edu)
  • In this work, we present our laboratory X-ray Talbot-Lau interferometry setup operating at 40 kVp and describe how we achieve the high sensitivity yet unrivalled by any other laboratory X-ray phase-contrast technique. (kit.edu)
  • This was followed by the assessment of their negative contrast sensitivity. (nih.gov)
  • We focused on the general contrast sensitivity assessment provided by the area under the log CSF (AULCSF). (arvojournals.org)
  • Also, these eye charts are limited (i) to one level of contrast, (ii) to a high spatial frequency content of the letters presented, and (iii) to the assessment of the central visual field. (psychophysics.uk)
  • Image quality assessment is understood to require detection and discrimination of masked signals, making contextual sensitivity and discrimination functions directly relevant. (westminster.ac.uk)
  • Binocular contrast summation exceeded probability summation in controls, but not in subjects with amblyopia (with or without strabismus) or strabismus without amblyopia who were able to fuse at the test distance. (frontiersin.org)
  • In the binocular measurements at2.5% contrast, sensitivity decreased in 49% of the core makers and 21% of the controls (P=0.002). (ebscohost.com)
  • As expected, uncorrected monocular contrast sensitivity was better in the emmetropic eyes than in aspheric eyes at all spatial frequency.Binocular summation improved the CS with respect to the monocular case with emmetropic eyes. (arvojournals.org)
  • Patients implanted with LALs bilaterally with induced asphericity in one eye showed normal binocular contrast sensitivity. (arvojournals.org)
  • A practical measure of binocularity is the binocular summation ratio BSR, which is the ratio of binocular contrast sensitivity to the contrast sensitivity of the better eye. (wikipedia.org)
  • Schrödinger (1926) put forth an equation for binocular brightness and contrast combination where each monocular input is weighted by the ratio of the signal strength from that eye to the sum of the signal from both eyes. (wikipedia.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)
  • 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)
  • Scotopic contract sensitivity showed the highest correlation with slant detection range (0.83). (semanticscholar.org)
  • and contrast sensitivity for the detection of an edge to estimate contrast sensitivity for larger objects. (auckland.ac.nz)
  • On-line experiment uses 2-interval forced-choice 'staircase' technique to determine contrast detection thresholds for. (merlot.org)
  • The contrast agent uses dissolved hyperpolarized xenon gas as a nonperturbing reporting medium, as xenon freely exchanges between aqueous solution and the perfluorocarbon interior of the droplets, which are spectroscopically distinguishable and allow for chemical exchange saturation transfer (CEST) detection of the agent. (bridge12.com)
  • Here, we reassessed the prior influences of signal probability and relevance on visual contrast detection using a reverse-correlation technique that quantifies how signal-like fluctuations in noise predict trial-to-trial variability in choice discarded by conventional analyses. (ox.ac.uk)
  • This dataset contains contrast measurements at luminances from 0.02 cd/m^2 (mesopic) to 7000 cd/m^2 (photopic). (cam.ac.uk)
  • The ability to detect luminance contrast. (thefreedictionary.com)
  • The ability to detect objects of low contrast is an important component of the visual system. (leatest.com)
  • Contrast thresholds were estimated by extrapolation of the CRF to zero microvolts. (nih.gov)
  • Sweep VEP contrast thresholds were shown empirically to be unaffected by changes in the range of contrast swept. (nih.gov)
  • Overall, contrast thresholds for the migraine group were lower than those in the control group. (mdpi.com)
  • 2002) reported significantly lower visual contrast sensitivity (VCS) in apartment residents exposed to tetrachloroethylene (perchloroethylene, or perc) compared to unexposed "matched" control subjects. (thefreedictionary.com)
  • Contrast sensitivity was significantly worse in patients with moderate glaucoma compared to those with early-stage glaucoma. (hindawi.com)
  • Pterygium surgery significantly reduces corneal topographic astigmatism and improves contrast sensitivity. (dovepress.com)
  • The contrast sensitivity of the core makers decreased significantly at both 2.5% and 0.6% contrast during the working day. (ebscohost.com)
  • Significantly better contrast sensitivity was observed with the aspheric lens, Dr. Petermeier said. (ophthalmologytimes.com)
  • Burton KB, Owsley C, Sloane ME (1993) Aging and neural spatial contrast sensitivity: photopic vision. (springer.com)
  • On contrast sensitivity measuring we used Ginsburg method (Vistech VCTS and Vector Vision CSV-1000 charts). (srce.hr)
  • Conclusions: The blurred vision caused by exposure to TEA can be documented by measuring contrast sensitivity. (ebscohost.com)
  • 2006) Measuring contrast sensitivity under different lighting conditions: comparison of three tests. (springer.com)
  • The aim of this report is to show how contrast sensitivity testing can contribute to functional examinations in strabismus and amblyopia. (srce.hr)
  • In visual deprivation amblyopia, both spatial localization and contrast sensitivity are affected. (srce.hr)
  • The CFF can be used to develop a logarithmic index of retinal sensitivity. (osapublishing.org)
  • In a group of subjects, contrast sensitivity at 6 cycles per degree was measured when viewing through holographic diffusers to produce different levels of scattering and with their spherical aberration simultaneously controlled using an adaptive-optics visual simulator. (um.es)
  • When the Cardiff Contrast Test is carried out at a distance of 50 cm the targets represent 1.9 cycles per degree (or 6/90, 20/300) and at a distance of 1 m the targets represent 3.8 cycles per degree (or 6/45, 20/150). (omtao.in)
  • However, there are several techniques that permit not only the evaluation of contrast sensitivity, but also allow researchers to obtain a more complete description of the overall functioning of the visual system (Campbell & Green, 1965). (druglibrary.org)
  • Chromatic contrast refers to the occurrence of differences in chromaticity (saturated, hue-full color) in a visual percept (scene, image, stimulus). (springer.com)
  • It may consist in differences across space ( spatial chromatic contrast ) or in changes of chromaticity across time ( temporal chromatic contrast ). (springer.com)
  • On the one hand, spatial chromatic contrast consists in the simultaneous occurrence of differences in chromaticity at different locations in space. (springer.com)
  • Like chromatic contrast, the term color contrast refers to the occurrence of differences in chromaticity, and both terms are often used interchangeably. (springer.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)
  • Specifically, the researchers looked for differences between the two groups of participants in activity reflecting contrast gain , the process by which cells in the retina adapt to variance in the light intensity of the visual scene so that the amount of information extracted from it can be maximized. (scienceblogs.com)
  • Median differences between Y-VA examinations (repeatability) were 0 LogMAR except between examinations 1 and 2 at the 25% contrast level, where it was 0.3 LogMAR. (diva-portal.org)
  • Conclusions: The new ClinicCSF application for iPad retina showed no significant differences with FACT test when the same contrast sensitivity steps were used. (upv.es)
  • But instead of the letters getting smaller on each successive line, it is the contrast of the letters (relative to the chart background) that decreases with each line. (allaboutvision.com)
  • The results on each patient were recorded in an evaluation chart which gives the contrast sensitivity curve. (srce.hr)
  • LEA NUMBERS® ETDRS-style Low Contrast Vision Chart with proportionally spaced (geometric progression) lines translucent low contrast letter chart with line sizes range from 20/200 to 20/10 (6/60 to 6/3) equivalent. (leatest.com)
  • 5. This finding supports the hypothesis that the sensitivities of the antagonistic centre and surround summating regions of ganglion cell receptive fields fall off as Gaussian functions of the distance from the field centre. (nih.gov)
  • 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)
  • The online VCS Test is a measure of one of the neurologic functions of vision called contrast . (survivingmold.com)
  • Contrast response functions in the visual wulst of the alert burrowing owl: a single-unit study. (semanticscholar.org)
  • Comparing the Shape of Contrast Sensitivity Functions for Normal and Low Vision. (psychophysics.uk)
  • If low contrast sensitivity is caused by higher-order aberrations, wavefront lenses or LASIK is the right choice. (firmoo.com)
  • Contrast sensitivity (CS) is affected by to optical reasons (aberrations, scatter, diffraction) or neural dysfunction (e.g., glaucoma, optic nerve diseases). (springer.com)
  • The early-generation multifocal IOLs, however, were shown to have noteworthy limitations, such as inferior contrast sensitivity and increased higher-order aberrations as compared with monofocal IOLs [ 3 ]. (hindawi.com)
  • It is known that contrast sensitivity reduces with the progression of age due to spherical aberrations [ 4 , 5 ]. (hindawi.com)
  • For elevated levels of scattering, the addition of small amounts of spherical aberration either does not decrease, or even may slightly increase, contrast sensitivity under some conditions. (um.es)
  • Simulated impairment of contrast sensitivity: performance and gaze behavior during locomotion through a built environment. (koreascience.or.kr)
  • A child with visual impairment who retains good contrast sensitivity will benefit from enlargement of tasks. (omtao.in)
  • 18, 2018 (HealthDay News) -- The risk of incident contrast sensitivity (CS) impairment is increased with factors such as cadmium exposure and older age, according to a study published online Sept. (thefreedictionary.com)
  • Dr Pamel provided detailed information about the clinical significance of contrast sensitivity testing for cataract documentation, evaluation of refractive surgery outcomes and the use of CS testing to aid in evaluating the need for and results of re-treatments after initial refractive surgery. (vectorvision.com)
  • For clinical studies using contrast sensitivity endpoints, it is critical to evaluate trends over time. (arvojournals.org)
  • The purpose of this study was to investigate the changes of refraction, VA and contrast sensitivity (CS) over time in high myopic school children after 1 week of overnight OK treatment. (elsevier.com)
  • Wah, TB & Mohidin, N 2014, ' Changes in refraction and contrast sensitivity following short term orthokeratology treatment in high myopic school children: A pilot study ', Sains Malaysiana , vol. 43, no. 5, pp. 733-738. (elsevier.com)
  • We provide the angular sensitivity expressed via the minimum resolvable refraction angle both in theory and experiment, and compare our data with other differential phase-contrast setups. (kit.edu)
  • Fun Frame occluding glasses are included with each Cardiff Test Contrast Sensitivity set and the set now has cards laminated on both sides. (omtao.in)
  • Driving at night is an example of an activity that requires good contrast sensitivity for safety. (allaboutvision.com)
  • Higher contrast sensitivity numbers are better, and if the red line is generally above the gray line you outperformed Dr. Shoemaker's healthy research subjects. (quantifiedbob.com)
  • To compare contrast sensitivity among participants undergoing wavefront-guided or wavefront-optimized photorefractive keratectomy (PRK) or LASIK for the treatment of myopia or myopic astigmatism 12 months after surgery. (healio.com)
  • We focused on elucidating the retinal adaptations to dim-light environments in these nocturnally active lampreys, using electroretinography to determine the temporal resolution (flicker fusion frequency, FFF) and temporal contrast sensitivity of enucleated eyecups at different temperatures and light intensities. (edu.au)
  • Almost every phenomenon in color vision involves contrasts between colors. (springer.com)
  • Since human color vision involves an achromatic luminance dimension and two chromatic dimensions, visual contrasts may occur in terms of luminance or chromaticity. (springer.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)
  • Comparison of Contrast Sensitivity at Near Between Functional Progressive Addition Lenses and Single Vision Lenses. (koreascience.or.kr)
  • Diabetes impacts your quality of vision, reducing your color and contrast sensitivity and even causing vision loss. (eyepromise.com)
  • Because loss of neurons or interruptions of their connective pathways in the mammalian visual system can, in contrast to certain amphibians and fish, lead to permanent loss of vision, studies of regeneration and plasticity in this system serve as valuable models for the reconstitution of other parts of the nervous system and as potential approaches to the diverse disorders that lead to visual loss. (mit.edu)
  • Our results show that there is greater variability in color vision and color contrast in NE-AMD patients compared to healthy patients. (kingdevicktest.com)
  • We designed and built a grating-based setup using a standard rotating-anode X-ray source and reaching comparable angular sensitivity as synchrotron-based setups. (spie.org)
  • Irlen Syndrome may cause a range of difficulties with sensitivity to light. (irlenuk.com)