Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Color Vision”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,711 records · Page 95Linked to original sources
PubMed2006

Cone weights for the two cone-opponent systems in peripheral vision and asymmetries of cone contrast sensitivity.

In understanding the basis of the changes in human color vision across eccentricity, one key piece of information remains unknown, whether the relative cone weights of the two cone opponent mechanisms vary. Here we measure detection threshold contours within three planes in a 3-dimensional cone contrast space to reveal the L, M and S-cone weights to the two cone opponent mechanisms, L/M and S/(L+M). We find these remain constant across eccentricity suggesting the underlying structures of the cone opponent mechanisms are invariant. The contrast sensitivities of two poles of the S-cone opponent mechanism also remain symmetrical, whereas small asymmetries develop in L/M opponency from about 15 degrees.

Color Perception↗
PubMed1975

Dominant cone-rod dystrophy.

Six generations of a family were studied extensively allowing the description of an autosomal dominant dystrophy of both rods and cones. The dystrophy is characterized by onset between ages 6 and 8 with gradual decrease in vision and progression to the point of no light perception. Abnormalities of color vision, visual field, refraction, fixation behavior, fundus appearance, fluorescein angiography, electroretinography, electrooculography and dark adaptation are presented. The importance of this family in the classification of inherited retinal dystrophies is stressed and the need for an expanded classification is discussed. The role of genetic counseling is stressed in such severe diseases.

Adult↗
PubMed1993

Color improves object recognition in normal and low vision.

Does color improve object recognition? If so, is the improvement greater for images with low spatial resolution in which there is less shape information? Do people with low visual acuity benefit more from color? Three experiments measured reaction time (RT) and accuracy for naming food objects displayed in 4 types of images: gray scale or color, and high or low spatial resolution (produced by blur). Normally sighted Ss had faster RTs with color, but the improvement was not significantly greater for images with low spatial resolution. Low vision subjects were also faster with color, but the difference did not depend significantly on acuity. In 2 additional experiments, it was found that the faster RTs for color stimuli were related to objects' prototypicality but not to their color diagnosticity. It was concluded that color does improve object recognition, and the mechanism is probably sensory rather than cognitive in origin.

Adult↗
PubMedDate not supplied

Alteration of visual function in impaired glucose tolerance.

People with impaired glucose tolerance are considered to be prone to diabetes. To evaluate their visual function we investigated colour vision with the Farnsworth-Munsell 100 Hue test and contrast sensitivity with Arden's grating cards in people with imparied glucose tolerance (IGT), people with normal glucose tolerance (NGT) and others with type II diabetes (NIDDM). Eyes with low vision or any anterior or posterior segment abnormalities were excluded. Contrast sensitivity and color vision differed significantly between the groups (p < 0.01). It thus appears that patients with IGT but without clinical diabetes could be followed up to see whether these alterations have any predictive value for the development of diabetes and diabetic retinopathy.

Color Perception↗
PubMed1994

The influence of contrast adaptation on color appearance.

Most models of color vision assume that signals from the three classes of cone receptor are recoded into only three independent post-receptoral channels: one that encodes luminance and two that encode color. Stimuli that are equated for their effects on two of the channels should be discriminable only to the remaining channel, and are thus assumed to isolate the responses of single channels. We used an asymmetric matching task to examine whether such models can account for changes in color appearance following adaptation to contrast--to temporal variations in luminance and chromaticity around a fixed mean luminance and chromaticity. The experiments extend to suprathreshold color appearance the threshold adaptation paradigm of Krauskopf, Williams and Heeley [(1982) Vision Research, 32, 1123-1131]. Adaptation changes the perceived color of chromatic test stimuli both by reducing their saturation (contrast) and by changing their hue (direction within the equiluminant plane). The saturation losses are largest for test stimuli that lie along the chromatic axis defining the adapting modulation, while the hue changes are rotations away from the adapting direction and toward an orthogonal direction within the S and L-M plane. Similar selective changes in both perceived color and perceived lightness occur following adaptation to stimuli that covary in luminance and chromaticity. The selectivity of the aftereffects for multiple directions within color-luminance space is inconsistent with sensitivity changes in only three independent channels. These aftereffects suggest instead that color appearance depends on channels that can be selectively tuned to any color-luminance direction, and that there are no directions that invariably isolate responses in only a single channel. We use the perceived color changes to examine the spectral sensitivities of the chromatic channels and to estimate the distribution of channels. We also examine how adaptation alters the contrast-response function, how it affects reaction times for luminance and chromatic contrast, the extent to which the aftereffects exhibit interocular transfer, and the way in which the perceived color changes differ from those induced by conventional light adaptation.

Adaptation, Ocular↗
PubMed1997

Schopenhauer on vision and the colors.

Arthur Schopenhauer (1788-1860) published his book, On Vision and the Colors in 1816. He started from Aristotle's linear color system and Goethe's three pairs of contrast colors. His work preceded Hering's theory of opponent colors but his path to insight was blocked by his anti-Newtonianism and his neo-Hellenistic attitude toward science. Because of his theory of the subjectivity of colors he was a forerunner of the psycho-physiological variant of neo-Kantianism.

Color↗
PubMedDate not supplied

Normal and dichromatic color discrimination measured with transient visual evoked potential.

It would be informative to have an electrophysiological method to study, in an objective way, the effects of mercury exposure and other neurotoxics on human color vision performance. The purpose of the present work was to study human color discrimination by measuring chromatic difference thresholds with visual evoked potential (VEP). Six young normal trichromats (24 +/- 1 years old) and one deutan (26 years old) were tested. The stimuli consisted of sinusoidal isoluminant chromatic gratings made from chromaticity pairs located along four different color directions centered on two reference points. Heterochromatic flicker photometry (HFP) protocol was used to obtain the isoluminance condition for every subject and for all chromaticity pairs. Spatial frequency was 2 cycles/deg. Presentation mode comprised onset (300 ms)/offset (700 ms) periods. As previously described, we found a negative deflection in the VEP which was related to the chromatic difference: as chromatic difference increased, amplitude increased and latency decreased. VEP response amplitude was plotted against distance in the CIE 1976 color space between the grating chromaticities and fitted with a regression line. We found color thresholds by extrapolating the fitting to null amplitude values. The thresholds were plotted in the CIE 1976 color space as MacAdam ellipses. In normal trichromats the ellipses had small size, low ellipticity, and were vertically oriented. In the deutan subject, the ellipses had large size, high ellipticity, and were oriented towards the deutan copunctal locus. The VEP thresholds were similar to those obtained using grating stimuli and psychophysical procedures, however smaller than those obtained using pseudoisochromatic stimuli (Mollon-Reffin method). We concluded that transient VEP amplitude as a function of contrast can be reliably used in objective studies of chromatic discrimination performance in normal and altered human subjects.

Adult↗
PubMed1998

Learning and homeostasis: drug addiction and the McCollough effect.

The contribution of conditioned responses (CRs) to homeostasis may be seen by examining seemingly disparate phenomena of color vision (aftereffects and chromatic adaptation) and drug addiction (withdrawal symptoms and tolerance). Color aftereffects may be elicited by nonchromatic stimuli previously paired with color (the McCollough effect, [ME]). Similarly, pharmacological aftereffects may be elicited by nonpharmacological stimuli previously paired with a drug (withdrawal symptoms). The authors summarize evidence indicating that both the ME and withdrawal symptoms are CRs. The chromatic CR is expressed as chromatic adaptation in the presence of color, and the ME in the absence of color. The pharmacological CR is expressed as pharmacological adaptation (tolerance) in the presence of the drug, and withdrawal symptoms in the absence of the drug. Both drug withdrawal symptoms and the ME are manifestations of the contribution of conditioning to normal homeostatic regulation. The authors discuss the implications of this conclusion for understanding regulatory processes and the evolution of behavioral mechanisms.

Color Perception↗
PubMed1987

Magnitude of lateral chromatic aberration across the retina of the human eye.

Lateral chromatic aberration was measured in the right eyes of four adult observers as the physical misalignment between perceptually aligned short- and long-wavelength targets. The magnitude of aberration generally increased with retinal eccentricity but remained less than 10 arcmin within 40 deg of the fovea. At 60 deg, lateral chromatic aberration increased to approximately 30 arcmin but was reducible by refractive correction in the two observers retested. The results are consistent with previous reports of a sizable region of reasonably good optical quality extending into the retinal midperiphery. Within this region, lateral chromatic aberration approximates the average spacing between adjacent retinal cones, indicating that it does not substantially limit peripheral color vision.

Adult↗
PubMedDate not supplied

Ocular side effects of antitubercular drugs - a focus on prevention, early detection and management.

Given the increasing prevalence of tuberculosis, antitubercular drugs frequently used are also associated with ocular toxicity. Ethambutol is the most commonly implicated drug. It is generally well tolerated, but known to cause optic neuritis, more specifically retro bulbar neuritis causing blurred vision, decreased visual acuity, central scotomas, and loss of red-green color vision. The exact mechanism of toxicity is not understood. Though optic neuritis due to ethmabutol is generally considered to be reversible upon prompt discontinuation of the drug, there are reports of reversible toxicity, particularly in the elderly population. Isoniazid can rarely cause retro bulbar neuritis. Dose relationship is usually not seen. Streptomycin is known to cause pseudo tumorcerebri. Thiacetazone can produce severe cutaneous reactions including Steven Johnson Syndrome affecting the skin and mucosa including conjunctiva. Educating the patients for early detection of the ocular manifestations and regular follow-ups are very essential.

Antitubercular Agents↗
PubMed1997

Visual function 5 years after optic neuritis: experience of the Optic Neuritis Treatment Trial. The Optic Neuritis Study Group.

OBJECTIVE: To assess the 5-year visual course, including the incidence of recurrent optic neuritis, in 454 patients enrolled in the Optic Neuritis Treatment Trial. METHODS: Five-year follow-up vision testing, which included measures of visual acuity, contrast sensitivity, visual field, and color vision, was completed for 397 (87%) of the 454 patients. RESULTS: Visual function test results in the eyes that experienced optic neuritis at study enrollment (affected eyes) were normal or only slightly abnormal after 5 years in most patients; the results did not significantly differ by treatment group (P=.37 for visual acuity). The visual acuity in the affected eyes was 20/25 or better in 87%, 20/25 to 20/40 in 7%, 20/50 to 20/190 in 3%, and 20/200 or worse in 3%. The recurrence of optic neuritis in either eye occurred in 28% of the patients and was more frequent in patients with multiple sclerosis (P=.001) and in patients without multiple sclerosis who were in the prednisone treatment group (P=.004). Most eyes with a recurrence retained normal or almost normal visual function. CONCLUSIONS: Most patients retained good to excellent vision in the 5 years following an attack of optic neuritis, even if the optic neuritis recurred. Recurrences were more frequent in patients with multiple sclerosis and in those treated with oral prednisone alone. The completion of the 5-year follow-up by the Optic Neuritis Treatment Trial cohort has not altered our management recommendations based on the results we reported earlier.

Administration, Oral↗
PubMed1989

Appearance of color matchings under various chromatic adaptation conditions.

Three chromatic reference stimuli (red, green, and blue) seen under five adaptation conditions (red, green, blue, achromatic, and darkness) were appearance-matched to subsequent color stimuli seen under achromatic conditions. The experimental results have been used to verify the opponent-color color-vision model and also to check the validity of some of the published transformation equations for predicting the tristimulus values of colors matched to a reference stimulus seen under different chromatic-adaptation conditions. It is concluded that the extant transformation laws are not sufficiently general to be applied to all adaptation conditions.

Adaptation, Ocular↗
PubMed2005

Responsiveness of the National Eye Institute Visual Function Questionnaire to progression to advanced age-related macular degeneration, vision loss, and lens opacity: AREDS Report no. 14.

OBJECTIVE: To describe the ability of the National Eye Institute Visual Function Questionnaire (NEI-VFQ) to detect meaningful change over time (responsiveness) to the primary Age-Related Eye Disease Study outcomes. METHODS: The 25-item NEI-VFQ plus appendix was administered at 2 visits at 1- to 4-year intervals to 4119 participants in the Age-Related Eye Disease Study. Events evaluated were progression to advanced age-related macular degeneration (AMD), visual acuity (VA) loss of at least 15 letters, and lens opacity progression. Responsiveness was measured by the t statistic, effect size (ES), responsiveness statistic, and area under the receiver operating characteristic curve. Variance components were used to estimate the contributions of events to variability of the NEI-VFQ score. RESULTS: Overall NEI-VFQ score was responsive to AMD progression (t = 14.0; P< .001; ES = 0.81) and VA (t = 16.2; P< .001; ES = 0.74). Mean changes ranged from 11 to 25 points for the subscales of general vision, near and distance activities, social functioning, mental health, role difficulties, dependency, and driving. The NEI-VFQ was unresponsive to lens opacity progression, although when the event occurred in the eye with the best vision at the first administration, the lens opacity ES was moderate for the color vision (ES = 0.62) and driving subscales (ES = 0.66). Progression to advanced AMD and VA loss contributed significantly to the variation in the mean difference in overall VFQ score. CONCLUSIONS: Changes in the NEI-VFQ overall and subscale scores of 10 points or more are associated with clinically significant changes in vision and AMD. This finding may assist the design of interventional studies of AMD and VA loss that include the NEI-VFQ as an outcome measure.

Aged↗
PubMed2005

Health related quality of life instruments for glaucoma: a comprehensive review.

Health related quality of life (HRQOL) outcome is becoming important and of interest for clinicians and patients alike. HRQOL can be affected immediately after the initial diagnosis of the disease through anxiety of blindness. Further impairment in various aspects of HRQOL is expected over time as the disease progresses, reducing daily activities. Without a gold standard for HRQOL construct in this population, a number of instruments have become available with different characteristics and foci. This article reviews published HRQOL instruments and their psychometric properties in glaucoma patients. Of the 10 instruments reviewed, 2 were generic, 4 were vision-specific and 4 were glaucoma-specific instruments. Overall, vision- and glaucoma-specific instruments appear to be more sensitive than generic instruments in detecting potential changes of HRQOL in the patients. The shortcoming of existing instruments, however, arises from being predominantly focused on physical functions while omitting other aspects relevant to patients HRQOL such as psychological and social well-being. In addition, many vision-specific instruments have inadequate coverage of important issues, such as peripheral and color vision, which are affected by glaucoma disease. Validation of the instruments using various magnitudes of visual field is warranted and further investigation of their responsiveness is required for them to be more useful for outcome evaluation in the clinical setting. Refinement of an instrument to enhance the incorporation of HRQOL in routine management of patients with glaucoma is briefly described.

Activities of Daily Living↗
PubMed1985

Characterization of the color related receptor mosaic in the ground squirrel retina.

Light microscopic and histochemical studies reveal that the retina of the European ground squirrel (Citellus citellus L.) contains a mosaic pattern of two cone types and a small population of rods. A minority (7%) of the cones can be characterized by their ellipsoids having larger diameters and increased staining density over the majority population. Exposure to green light selectively elicited intense NBT-diformazan labeling in the major population of cones while the larger diameter cone type was labeled after blue illumination. The two cone subpopulations are probably the blue and green cone types of ground squirrel protanopic color vision.

Animals↗
PubMed2002

Time-dependent changes of rod influence on hue perception.

Hue-naming was used in conjunction with a probe-flash procedure to determine the time-course of rod-mediated effects on hue appearance across the spectrum. Two types of rod influence on hue are distinguishable on the basis of differences in both spectral specificity and time course of effect: (1) a "faster" rod influence enhances green relative to red and (2) a "slower" rod influence enhances short-wavelength red relative to green and blue relative to yellow. The results show that there are separable rod hue biases that operate over different time courses and that the overall rod influence on hue appearance depends importantly on the temporal properties of the stimuli, presumably because rods interact in different ways with different portions of the neural pathways that mediate human color vision.

Adaptation, Ocular↗
PubMed2001

Target detection in scientific visualization.

Three experiments were conducted to test participants' ability to detect targets in colored spatial displays using 7-level bipolar scales. Experiment 1 assessed the ability of participants to detect high or low targets using 12 scales whose poles either were directly opposed in color space or had a primary and an intermediate hue at each pole. Experiment 2 used 8 scales whose arms were orthogonal in color space. Experiment 3 examined the simultaneous detection of high and low targets. Although there are notable exceptions, scales that are close to or above the horizontal (red-green) axis in color space perform best. Of the scales with orthogonal arms, those that are oriented downward, toward the blues, in color space are least satisfactory. Scales that are asymmetrically effective are common, and applications requiring good detectability at both extremes must take this into account. The results are discussed in the context of the evolution of trichromatic color vision.

Adult↗
PubMed1980

The Bezold-Brücke phenomenon for purple colors.

A bipartite stimulus 2 degrees in diameter was used to study the Bezold-Brücke phenomenon for purple colors. A mixture of 460 nm and 667 nm in one half at a given luminance was matched with a mixture of the same two wavelengths at a luminance level 10 times higher. The hue of the 667-nm stimulus was not affected by the change in luminance. There is one mixture of red and blue which remains unchanged in hue as the luminance increases. Reddish purples shift toward red and bluish purples toward blue. These findings are consistent with a zone theory of color vision such as proposed by Adams.

Color Perception↗