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At least 19 recordsLinked to original sources
PubMed2000

Molecular genetics of color vision and color vision defects.

Color is an extremely important component of the information that we gather with our eyes. Most of us use color so automatically that we fail to appreciate how important it is in our daily activities. It serves as a nonlinguistic code that gives us instant information about the world around us. From observing color, for example, we can find the bee sting on an infant's arm even before it begins to swell by looking for the little spot where the infant's skin is red. We know when fruit is ripe; the ripe banana is yellow not green. We know when meat is cooked because it is no longer red. When watching a football game, we can instantly keep track of the players on opposing teams from the colors of their uniforms. Using color, we know from a distance which car is ours in the parking lot--it is the blue one--and whether we will need to stop at the distant traffic light, even at night, when we cannot see the relative positions of red and green lights.

Color Perception↗
PubMed1996

Visual pigment gene structure and the severity of color vision defects.

Rearrangements of the visual pigment genes are associated with defective color vision and with differences between types of red-green color blindness. Among individuals within the most common category of defective color vision, deuteranomaly, there is a large variation in the severity of color vision loss. An examination of specific photopigment gene sites responsible for tuning photopigment absorption spectra revealed differences that predict these variations in the color defect. The results indicate that the severity of the defect in deuteranomalous color vision depends on the degree of similarity among the residual photopigments that serve vision in the color-anomalous eye.

Blotting, Southern↗
PubMed1989

What do color vision defectives say about everyday tasks?

A lengthy questionnaire was administered to 102 people with defective color vision and to an equal number of people with normal color vision. The questionnaire asked about the subjects' awareness of their defect and their knowledge of defective color vision as well as exploring the difficulties they experience with color at work and in pursuing leisure activities. The questionnaire was administered in the consulting room under conditions that might be expected to elicit frank replies. Nearly 90% of dichromats and up to two-thirds of anomalous trichomats reported difficulties with everyday tasks that involve color, nearly one-half of the dichromats and one in five anomalous trichromats reported difficulty with traffic lights, and similar proportions reported color difficulties in their present jobs. Substantial numbers reported that their color vision defect had affected their choice of career and many had been excluded from a chosen occupation. The screening of color vision in schools and provision of appropriate career counselling is urged.

Activities of Daily Living↗
PubMed2002

Color and defective color vision as factors in the conspicuity of signs and signals.

The conspicuity of road traffic signs and signals for a group of observers with the color vision defect of deuteranopia is compared with that for a control group of observers with normal color vision. Conspicuity was measured by the proportion of reports of target objects detected in 300-ms presentations of projected slides of road scenes. There were two instructions, one designed to measure attention conspicuity and the other, search conspicuity. The attention conspicuity of red, orange, and green color-coded traffic control devices was significantly less for deuteranopes than for the observers with normal color vision, but this was not true for yellow and blue color-coded signs. This result is consistent with our understanding of the color perceptions of deuteranopes. The reduction of conspicuity was not so great for the search conspicuity condition. We conclude that redundant color coding does contribute to the conspicuity of signs and signals and that deuteranopes--and probably those with other severe forms of defective color vision--have a significantly reduced ability to notice colored targets, such as road signs and signals, in complex visual environments. The actual and potential application of this work is in the design of signs so they are conspicuous, especially when the user group includes people with defective color vision.

Adolescent↗
PubMed2007

Can color vision defective subjects who pass the farnsworth lantern test recognize surface color codes?

INTRODUCTION: The International Civil Aviation Organization requires that pilots be able to distinguish the colors used in air navigation and in particular be able to identify the colors of signal lights. Most national aviation authorities use a lantern test to assess the ability of applicants for a pilot's license who have abnormal color vision to recognize the colors of signal lights. However, color-coding is now widely used in aviation systems other than signal lights. Color is used in tarmac markings, maps, manuals, and electronic flight instrument displays. These color codes can use 10 or more colors, many more than the 3 to 5 used for signal lights. This study investigated whether people with defective color vision (DCV) who pass the Farnsworth lantern test can recognize the main colors used for surface color codes. METHODS: There were 99 subjects with DCV who were tested using the Optec 900 version of the Farnsworth lantern test and also named the colors of a set of 10 surface colors that varied in shape (dots and lines) and size (3 sizes; angular diameters 0.27, 1.0, and 2.4 degrees; angular widths 0.14, 0.27, and 0.50 degrees). A control group of 20 subjects with normal color vision also named the surface colors. RESULTS: Of the DCV subjects, 19% passed the Farnsworth lantern test, of whom 74% made no errors with the surface colors. The other 26% made few errors (up to 5 errors in 120 presentations) and those errors were mostly to confuse red, orange, and brown. The subjects with normal color vision made no errors naming the surface colors. CONCLUSION: Those who pass the Farnsworth lantern test can recognize the colors of a 10-color surface color code with few or no errors. This is because the small (2.9-min arc) stimulus of the lantern test presents a more difficult task than the larger surface colors.

Adolescent↗
PubMedDate not supplied

A novel mutation in the short-wavelength-sensitive cone pigment gene associated with a tritan color vision defect.

Inherited tritan color vision deficiency is caused by defects in the function of the short-wavelength-sensitive (S) cones. This heterozygous group of disorders has an autosomal dominant pattern of inheritance. Amino acid variations of the S cone opsin are rare and all that have been identified thus far are associated with inherited tritan color vision defects. Here we report the identification of a 30-year-old male who made errors on standard color vision tests consistent with the presence of a mild tritan color vision deficiency. We tested the hypothesis that his color vision impairment was due to a mutation in the S cone photopigment gene. He was found to be heterozygous for a mutation that caused the amino acid proline to be substituted in place of a highly conserved leucine at amino acid position 56 in the S cone opsin. This mutation was absent in 564 S cone photopigment genes from 282 subjects who did not make tritan errors. Thus, we conclude that this mutation disrupts the normal function of S cones.

Adult↗
PubMed1982

Color vision defects in pigmentary retinal dystrophy.

Color vision was studied, using the Farnsworth Panel D-15 test, in 72 patients (115 eyes) with primary pigmentary retina dystrophy of autosomal recessive inheritance, and the results were correlated with the visual acuity and visual field. The incidence of color vision defects and the degree of disturbance increased as the visual acuity and the visual field deteriorated. However, even in cases with the visual acuity better than 0.7, type III acquired blue-yellow defect was found in 22% of the cases. This type of color vision defect was also found in 52% of the cases with the visual acuity between 0.4 and 0.6. In the group with the visual acuity of 0.1 or less, total achromatopsia was found in 64% of the cases. The increment thresholds of the blue and green cone mechanisms in the fovea were determined by the two-color threshold technique of Stiles in 12 patients with the visual acuity better than 0.8. The thresholds of the blue cone mechanism (pi 1) and of the green cone mechanism (pi 4) were found to be elevated over the normal values. The increases in the former and the latter thresholds were correlated linearly with the slope of the regression of 0.64. The increase in the threshold of the blue cone mechanism was more pronounced than that of the green cone mechanism. Due to the difference in the density of both cones in the fovea, this result does not necessarily support the hypothesis that the blue cone mechanism is affected preferentially more than the green cone mechanism.

Adolescent↗
PubMed1986

Acquired color vision defects and self monitoring of blood sugar in diabetics.

Color vision defects are common in diabetic patients and may precede visible retinal changes. More severe retinopathy is generally associated with more severe color vision defects. Many diabetics err when making color comparisons using self monitoring techniques. Optometrists can play an important role in diabetes patient management by monitoring color vision defects and making patients aware of problems or potential problems in self monitoring. Care must be taken in color vision evaluation as the most frequent acquired color vision defect in diabetics is a blue-yellow axis defect. Most commonly employed color vision tests are not sensitive in detecting this defect.

Aged↗
PubMed1990

The proportion of various types of congenital color vision defects.

One hundred and three color vision defective subjects were screened from 3456 middle school students with pseudoisochromatic plate test. One hundred subjects out of them were further examined with a test battery including Panel D-15 and FM 100-hue test and Neitz anomaloscope test. It was found that there were 21 protanopes (P), 3 extremely protanomalous (EPA), 13 protanomalous (PA), 25 deutenopes (D), 5 extremely deuteranomalous (EDA), 28 deuteranomalous (DA), 6 unclassified subjects in our investigation. The proportion of various types of congenital color vision defects was P:EPA:PA:D:EDA:DA = 1.00:0.14:0.62:1.19:0.24:1.33.

Adolescent↗
PubMed2003

Color vision.

Many visual disorders produce acquired color vision defects. Color vision theory emphasizes several stages of visual processing: prereceptoral filters (lens, macular pigment, pupil), cone photopigments (L-, M-, and S-cones), and postreceptoral processes (red-green, S-cone, and luminance channels). Congenital color defects, which affect 8% to 10% of males and 0.4% to 0.5% of females, result from alterations in the photopigment absorption spectra or the absence of one or more photopigments. The most common defects are color vision deficiencies (protan and deutan defects), which are milder than the rarer achromatopsias (complete loss of color vision). Acquired color vision defects can be attributed to a number of different causes: alteration of prereceptoral filters, reduced cone photopigment optical density, greater loss of one cone type than the others, and disruption of postreceptoral processes. Acquired color vision defects have been divided into three classes: type 1, red-green defect with scotopization; type 2, red-green defect without scotopization; and type 3, blue defects (with or without pseudoprotanomaly). Blue defects are usually type 3 acquired defects because congenital tritan defects have an incidence of one in several tens of thousands. Red-green defects can be acquired or congenital, and ruling out acquired defects can require a battery of tests (plates and arrangement tests, anomaloscopy, perhaps genetic analysis). Color vision tests must be administered carefully (with a standard illuminant and protocol), and pupillary miosis or high lens density should be noted and their possible effects considered when interpreting test results. Plate tests provide a simple screening method but do not provide a diagnosis. Arrangement tests and anomaloscope testing take more time and make greater demands on the tester, but they provide a more thorough evaluation. When standard protocols are followed and results are interpreted in terms of prereceptoral filters, photopigment optical density, cone loss, and disruption of postreceptoral processes, a battery of color vision tests can be useful in the differential diagnosis, after progression of the disease, and for evaluating the effectiveness of treatment.

Color Perception↗
PubMed1986

Color vision defects in early diabetic retinopathy.

Four color vision tests were used to assess color vision in 51 insulin-dependent diabetic patients and 41 normal controls. Right and left eyes of diabetic patients, selected because they had minimal retinopathy, had significantly more color vision defects than controls on Lanthony desaturated D-15, Farnsworth-Munsell 100-Hue, and chromagraph tests. The 100-Hue scores were significantly higher in both right and left eyes of diabetic patients than in controls. There were no significant associations between presence or absence of a color vision defect and age, sex, age at onset, duration of diabetes, or its metabolic control.

Adult↗
PubMedDate not supplied

An artist with a color vision defect: Charles Meryon.

Charles Meryon, an important artist of the 19th century, had a congenital defect in color vision. Meryon recognized this defect during his study of art, and he gradually gave up painting in favor of etching. This biographical article includes reproductions of some of Meryon's etchings and one oil painting. "Ghost Ship." Two palates display the principal colors of the spectrum, as seen normally and as seen with a color vision defect. "Ghost Ship" reveals the color-defective artist's typical preference for blue and yellow.

Art↗
PubMed1988

Color vision defects in ocular hypertension and glaucoma. Quantification with a computer-driven color television system.

In order to detect early defects of color vision caused by increased intraocular pressure, a computer graphics device and color monitor system were used to measure color contrast sensitivity. The system determines the threshold chrominance of a colored grating in which there is no change in luminance. The study included 13 control subjects aged 10 to 57 years and 19 patients with ocular hypertension or glaucoma aged 20 to 58 years. In the 13 eyes with visual field loss, color contrast sensitivity was profoundly reduced when the grating colors fell on a tritan color confusion line. In the eyes without visual field loss, tritan color contrast sensitivity was reduced to an average level considerably below the extreme limits of the control group. These results were compared with those of other color vision tests and diagnostic criteria for glaucoma. The findings suggest that among the tests used, color contrast sensitivity testing was able to discriminate most effectively between patients who had retinal damage and the normal population.

Color Perception Tests↗