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PubMedDate not supplied

The importance of controlled illumination in color vision testing in a pediatric ophthalmology clinical practice.

The AO-HRR pseudoisochromatic plates are commonly used for color vision testing in pediatric ophthalmology; however, the recommended procedure for obtaining proper illumination (a completely darkened room and standard illuminant) is typically not followed. To evaluate the role of the illuminant in clinical testing with the AO-HRR, 132 children, ages 3 to 16 years, were tested with and without the recommended illuminant (MacBeth Easel Lamp) and with the self-illuminated APT-5 Color Vision Tester. Twenty-two failed the AO-HRR with the recommended illuminant; 28 failed the AO-HRR without the illuminant. Only 13 failed the APT-5. The Cochran Q test for three related samples showed that the differences among the three groups were significant (Q = 17.1, P < .001). Diagnostic evaluation following clinical screening indicated that the differences among the tests were primarily due to false alarms, which were greatest without the recommended illuminant and least with the APT-5. These results demonstrate the importance of controlled illumination in color vision testing, either by using the recommended illumination with the AO-HRR or a self-illuminated test such as the APT-5.

Adolescent↗
PubMedDate not supplied

A model of color vision based on cortical reentry.

It is known that the perceived color of an object depends on the context in which it is viewed, its reflectance properties and the spectral distribution of the illuminating light. What is not known, however, is how the visual system functions so that color percepts depend upon the integration of local and contextual cues. While phenomenological theories of color vision exist, robust neurally based theories consistent with psychophysical observations are sparse. In the present study we develop such a theory and establish its self-consistency by computer simulations of cerebral cortical areas involved in color perception. The simulations test the hypothesis that long-range reciprocal connections within and between cortical areas mediate a dynamic process of reentry that integrates contextual cues into the color percept. When stimuli similar to those used in psychophysical testing of contextual influence were used, firing patterns consistent with psychophysical data on color constancy and color induction in humans were observed. Selective disruption of reciprocal inter- or intra-areal connections reduced the correspondence between the model's responses and the psychophysical data. The findings are consistent with the proposal that reentrant interactions within and between cortical areas provide a major basis for the context-sensitive aspects of color vision.

Animals↗
PubMed2002

Color vision perception in the capuchin monkey (Cebus apella): a re-evaluation of procedures using Munsell papers.

In previous experiments based on color vision discrimination of Munsell chips, Pessoa et al. (Behav Brain Res 1997;89:285-8) presented evidence of trichromatic color vision in capuchin monkeys. However, the possibility of subjects using brightness cues was not eliminated. The purpose of the present study was to reassess the color perception in Cebus apella in a similar behavioral paradigm, but using a range of brightness values at each tested hue. We now report that male capuchins show a dichromatic behavior. The results are discussed in terms of the hypothesis of male dichromatism in the New World monkey, the biological role of color vision and cognitive abilities of capuchin monkeys.

Adult↗
PubMed1988

Mechanisms of color vision.

We review the physiological and psychophysical research on mechanisms of color vision. Psychophysical work has led to the formulation of explicit theories of the early stages of color vision. The principal postulates of these theories have been confirmed by physiologists (e.g., the existence of three classes of receptors and second-stage mechanisms in which the signals from these receptors are compared), but some important features of the psychophysical scheme have found limited physiological support. One such issue is the absence of the unitary "achromatic" mechanism required by psychophysicists. We know a good deal less about the chromatic analyses that occur beyond these early stages. Although physiologists have devoted much effort to the study of cortical mechanisms, little of this work has been guided by clear ideas of the tasks performed by them. The provision of color constancy and the ability to segment scenes are perhaps the foremost concerns of chromatic mechanisms, and recent psychophysical work bearing on these problems offers physiologists clearer guidance on what to seek with their electrodes.

Animals↗
PubMed1988

A new test for screening color vision: concurrent validity and utility.

Recognizing the need for an effective test for screening color vision in young children, we have developed a new pseudoisochromatic (PIC) plate test which is useful for a wide variety of observers at different ages. The test consists of four plates and responses can be used to categorize color vision as normal or as either red-green or blue-yellow defective. Results of this validation study with adults, both color normal and red-green defective, show a high degree of correlation between the new test and the Nagel anomaloscope: there were no false positives and only a few false negatives, which occurred with mild deuteranomalous observers. The validity of the test compares favorably to the Ishihara, F-2, and the AO-HRR screening plates. Results with toddlers (3 to 6 years) indicate that the task demands of the test are well suited for testing young children. The percentage of color defectives identified in the toddler sample using the new test is closer to the adult prevalence than results obtained with the F-2 and AO-HRR screening plates, which gave dramatically higher failure rates. The new test is culture-free and can be administered rapidly to both verbal and nonverbal observers using pointing or preferential looking.

Adult↗
PubMed1996

Prevalence of congenital red-green color vision defects in Arab boys from Riyadh, Saudi Arabia.

The prevalence of congenital red-green color vision defects (CVDS) is both racial and gender dependent. Red-green color vision defects (CVDS) have been screened for among Arab boys from Riyadh, Saudi Arabia, by using both the Ishihara plates and the D 15 test. The results indicate a prevalence of 2.93%. Deutan defect was present in 1.95% of the subjects, protan defect in 0.49% and unclassified color defect in 0.49%. This result confirms the previously reported low prevalence of congenital red-green CVDS among adult Arab males from the central region of Saudi Arabia.

Adolescent↗
PubMedDate not supplied

Color vision deficiencies: a common sign of intoxication in chronically digoxin-treated patients.

On the basis of anamnestic data from digitalis-intoxicated patients, rates of general disorders of vision between 6 and 20% have been reported. We used a psychophysical method, an automatically evaluated Farnsworth's Munsell 100-Hue Test, to detect color vision deficiencies in patients who received beta-methyldigoxin or beta-acetyldigoxin for at least 4 weeks as maintenance therapy. Patients were subgrouped according to serum digoxin concentrations measured by radioimmunoassay. There was a significant correlation between extent and rate of color vision deficiencies and serum digoxin concentrations. About 80% of the intoxicated patients showed generalized color vision deficiencies.

Acetyldigoxins↗
PubMed1994

Spectral sensitivity, photopigments, and color vision in the guinea pig (Cavia porcellus).

Behavioral discrimination tests and electroretinogram (ERG) flicker photometry were used to measure spectral sensitivity and to define the spectral mechanisms of the guinea pig (Cavia porcellus). Results from these 2 approaches converge to indicate that guinea pig retinas contain rods with peak sensitivity of about 494 nm and 2 classes of cone having peak sensitivities of about 429 nm and 529 nm. The presence of 2 classes of cones suggests a retinal basis for a color vision capacity. Behavioral tests of color vision were conducted that verified this prediction: Guinea pigs have dichromatic color vision with a spectral neutral point centered at about 480 nm. The cone pigment complement of the guinea pig is different from that known to characterize other rodents.

Animals↗
PubMed1996

Melatonin regulation in humans with color vision deficiencies.

Light can induce an acute suppression and/or circadian phase shift of plasma melatonin levels in subjects with normal color vision. It is not known whether this photic suppression requires an integrated response from all photoreceptors or from a specialized subset of photoreceptors. To determine whether normal cone photoreceptor systems are necessary for light-induced melatonin suppression, we tested whether color vision-dificient human subjects experience light-induced melatonin suppression. In 1 study, 14 red-green color vision-deficient subjects and 7 normal controls were exposed to a 90-min, 200-lux, white light stimulus from 0200-0330 h. Melatonin suppression was observed in the controls (t = -7.04; P < 0.001), all color vision-deficient subjects (t = -4.76; P < 0.001), protanopic observers (t = -6.23; P < 0.005), and deuteranopic observers (t = -3.48; P < 0.05), with no significant difference in the magnitude of suppression between groups. In a second study, 6 red/green color vision-deficient males and 6 controls were exposed to a broad band green light stimulus (120 nm with lambda max 507 nm; mean +/- SEM, 305 +/- 10 lux) or darkness from 0030-0100 h. Hourly melatonin profiles (2000-1000 h) were not significantly different in onset, offset, or duration between the two groups. Melatonin suppression was also observed after exposure to the green light source at 0100 h (color vision deficient: t = -2.3; df = 5; P < 0.05; controls: t = -3.61; df = 5; P < 0.01) and 0115 h (color vision deficient: t = -2.74; df = 5; P < 0.05; controls: t = -3.57; df = 5; P < 0.01). These findings suggest that a normal trichromatic visual system is not necessary for light-mediated neuroendocrine regulation.

Adult↗
PubMedDate not supplied

[Genetics of congenital color vision defects. II. Rare types of color blindness].

Between the rare types of colour blindness, the known best are defects of blue colour vision, which are called tritanopia or trinanomaly (tritanomalous trichromacy). Their incidence is 1 in 500 and they are inherited in autosomal dominant way with incomplete penetrance. The basis of them are mutations of the short (blue) wavelength sensitive visual pigment gene. The gene has been mapped on the chromosome 7 and has already been cloned and sequenced. However, the loci heterogeneity should not be excluded in that condition. Another rare type of colour blindness in blue cone monochromacy. It is based on the cone sensitivity to short (blue) wavelength only. The condition is inherited in X-linked recessive way and it is known, that it can be caused by 2 different mechanisms. The first one--two-step pathway--consists of green cone pigment gene deletion, and point mutation of red cone pigment gene. The second one--one-step pathway--arose by deletion of regulatory sequence of both genes of visual pigments, mapped on the X chromosome. Different types of total and partial achromatopsia are also described. The best known ones are: rod monochromacy, which is inherited in autosomal recessive way and consist of rod vision only, and cone dystrophy, usually inherited in X-linked recessive way.

Chromosome Mapping↗
PubMed1954

[Color vision].

Explore the source record for details and available documents.

Color Perception↗
PubMed2003

Traffic signal color recognition is a problem for both protan and deutan color-vision deficients.

We investigated the effect of color-vision deficiency on reaction times and accuracy of identification of traffic light signals. Participants were 20 color-normal and 49 color-deficient males, the latter divided into subgroups of different severity and type. Participants performed a tracking task. At random intervals, stimuli simulating standard traffic light signals were presented against a white background at 5 degrees to right or left. Participants identified stimulus color (red/yellow/green) by pressing an appropriate response button. Mean response times for color normals were 525, 410, and 450 ms for red, yellow, and green lights, respectively. For color deficients, response times to red lights increased with increase in severity of color deficiency, with deutans performing worse than protans of similar severity: response times of deuteranopes and protanopes were 53% and 35% longer than those of color normals. A similar pattern occurred for yellow lights, with deuteranopes and protanopes having increased response times of 85% and 53%, respectively. For green lights, response times of all groups were similar. Error rates showed patterns similar to those of response times. Contrary to previous studies, deutans performed much worse than protans of similar severity. Actual or potential applications of this research include traffic signal design and driver licensing.

Accidents, Traffic↗
PubMedDate not supplied

FDA regulation of labeling and promotional claims in therapeutic color vision devices: a tutorial.

The Food and Drug Administration (FDA) is responsible for determining whether medical device manufacturers have provided reasonable assurance, based on valid scientific evidence, that new devices are safe and effective for their intended use before they are introduced into the U.S. market. Most existing color vision devices pose so little risk that their manufacturers are not required to submit a premarket notification [510(k)] to FDA prior to market. However, even low-risk devices may not be acceptable if they are marketed on the basis of misleading or excessive claims. Although most color vision devices are diagnostic, two types that are therapeutic rather than diagnostic are colored lenses intended to improve deficient color vision and colored lenses intended to improve reading performance. Both of these devices have presented special regulatory challenges to FDA because the intended uses and effectiveness claims initially proposed by the manufacturers were not supported by valid scientific evidence. In each instance, however, FDA worked with the manufacturer to restrict labeling and promotional claims in ways that were consistent with the available device performance data and that allowed for the legal marketing of the device.

Color Perception↗
PubMed1990

[Color vision defects in chronic open angle glaucoma].

Glaucomatous optic nerve atrophy is associated with morphological and psychophysical changes. Using Roth's Besancon anomalometer, the Farnsworth 100 hue test and Nagel's anomaloscope, we examined color vision in 86 eyes of 51 patients suffering from chronic open-angle glaucoma and 57 eyes of 41 normal subjects. In the normal control group, blue und green sensitivity decreased and, accordingly, the anomaly quotient tested with Nagel's anomaloscope increased significantly (p less than 0.00001) with age. If the glaucoma and control groups were matched for age, refractive error and central visual acuity, decreasing blue sensitivity significantly (p less than 0.05) correlated with diminished visibility of the retinal nerve fiber bundles, a higher morphological glaucoma stage and larger perimetric defects. The presence and depth of localized defects of the retinal nerve fiber layer were not significantly different in glaucoma subgroups with lower and higher blue sensitivity, respectively, when the subgroups were matched for age, refractive error and visual acuity. No papillomorphologic marker for the cyanodyschromatopsia was detected. Red-green color vision was not significantly different between the normal and glaucoma eyes. Testing of blue color vision as an additional method is useful in the differential diagnosis of beginning glaucomatous optic nerve damage in patients with clear optic media and lack of macular changes.

Adult↗