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Assessing color vision loss among solvent-exposed workers.

Acquired color vision loss has been associated with exposure to organic solvents in the workplace. However, not all tests of chromatic discrimination loss are designed to detect acquired, as opposed to congenital, loss. The Lanthony D-15 desaturated panel (D-15-d), a simple 15 cap color arrangement test, designed to identify mild acquired dyschromatopsia, can be administered rapidly in the field, under standard conditions. The objective of the present study was to evaluate the D-15-d among 23 solvent-exposed workers of a paint manufacturing plant, by comparing the results obtained with the D-15-d to those obtained with the Farnsworth-Munsell 100 Hue (FM-100), a highly sensitive measure of color vision loss. The D-15-d revealed a significantly higher prevalence of dyschromatopsia among the ten highly exposed workers (80%) as compared to the 13 moderately exposed workers (30.8%); FM-100 results revealed one false positive. All dyschromatopic workers presented blue-yellow loss; the FM-100 detected eight complex patterns, while the D-15-d identified 5. Comparison of D-15-d and FM-100 scores were highly correlated (corr. coeff. 0.87; p less than 0.001). Multiple regression analyses showed both scores to be significantly related to age and exposure level. The findings of this study indicate that the D-15-d is an adequate instrument for field study batteries. However, the FM-100 should be used for more detailed assessment.

Color Perception↗

[Study on FM100-HUE color vision in male workers exposed to lower concentration of carbon disulfide].

The effect of CS2 on color vision in workers exposed to CS2 was explored. The color discrimination in 191 exposed and 93 non-exposed male workers was studied by a Farnsworth Munsell 100-HUE (FM100-HUE) test. The results showed that the time weighted average (TWA) concentration of CS2, determined by Japan GC-17A gas chromatography, was (14.75 +/- 6.89) mg/m3 in a long rayon workshop and (16.30 +/- 5.42) mg/m3 in a short rayon workshop. Higher FM100-HUE color vision score was often in the exposed group (106.9) than in the controls (78.3). The discrimination to green and blue zone was also significantly impaired (P < 0.05). It is concluded that the color vision was disturbed in workers exposed to CS2. The workers should be followed by health surveillance.

Adult↗

[Genetics of congenital color vision defects. I. Common types of color blindness].

Normal human colour vision is based on the presence of 3 kinds of cones containing 3 different visual pigments, sensitive to short (blue), middle (green) and long (red) wavelengths. Congenital defects of colour vision are based on handicap or total loss of these pigments' function, usually a result of changes in their coding genes. The common types of colour blindness, referred to red-green axis, are present in about 8% of males and 0.44% of females. 3/4 of them are deuteranopes or deuteranomalous trichromats and 1/4 of them are protanopes or protanomalous trichromats. All of them are inherited in X-linked recessive way. The genes have been already mapped and sequenced. The cause of the great majority of their changes is nonhomologous recombination, which produces a gene deletion or creates the red-green or green-red hybrid genes. The result of that is the production of visual pigment with partly or totally changed spectral sensitivity.

Color Vision Defects↗

Color vision defects in adrenomyeloneuropathy.

The relationship between abnormal color vision and adrenomyeloneuropathy (AMN) was investigated in 27 AMN patients and 31 age-matched controls by using the Farnsworth-Munsell 100 Hue test. Twelve (44%) of 27 patients showed test scores significantly above normal. The axes of bipolarity determined by the testing differed widely between the patients with abnormal scores, compatible with the notion that different alterations in visual pigment genes occur in different AMN kindreds. These observations confirm our earlier impression that the frequency of abnormal color vision is increased in these kindreds, and it supports our contentions that (1) AMN (and its companion, adrenoleukodystrophy) are very closely linked to the visual pigment loci at Xq28 and (2) this proximity might provide the opportunity to observe contiguous gene defects.

Adrenal Gland Diseases↗

Severity of color vision defects: electroretinographic (ERG), molecular and behavioral studies.

Earlier research on phenotype/genotype relationships in color vision has shown imperfect predictability of color matching from the photopigment spectral sensitivities inferred from molecular genetic analysis. We previously observed that not all of the genes of the X-chromosome linked photopigment gene locus are expressed in the retina. Since sequence analysis of DNA does not necessarily reveal which of the genes are expressed into photopigments, we used ERG spectral sensitivities and adaptation measurements to assess expressed photopigment complement. Many deuteranomalous subjects had L, M, and L-M hybrid genes. The ERG results showed that M pigment is not present in measurable quantities in deutan subjects. Using these results to determine gene expression improved the correlations between inferred pigment separation and color matching. Furthermore, we found a subject who had normal L and M genes and normal proximal promoter sequences, yet he had a single photopigment (M) by ERG and tested as a protanope. These results demonstrate the utility of ERG measurements in studies of molecular genetics of color vision deficiencies, and further support the conclusion that not all genes are expressed in color deficient subjects. In particular, deuteranomaly requires a presently unknown mechanism of selective expression which excludes normal M genes and allows expression of L-M hybrid genes in one cone type, and the normal L in another.

Adaptation, Ocular↗

[Recent trends and developments in the clinical study of color vision--the 2-comparison method].

Modern anomaloscopes with four independent light channels (i.e., the Besançon Anomalometer which was presented in 1980 at the DOG) allow accurate examinations of color vision. In our routine clinical examination, we use two metameric equations: the red-green Rayleigh equation and the blue-green Moreland equation. This two-equation method permits the diagnosis of congenital and acquired color vision defects in a precise quantitative way. In both equations the goal of the examination is to measure the absolute matching range. The diagnosis is abnormal color vision if the absolute matching range is shifted and/or enlarged in one or both of the two metameric equations. A computer-controlled clinical examination of color vision, which will make the procedure simpler and shorter for the patient, is presently being developed.

Adolescent↗

Trichromatic color vision with only two spectrally distinct photopigments.

Protanomaly is a common, X-linked abnormality of color vision. Like people with normal color vision, protanomalous observers are trichromatic, but their ability to discriminate colors in the red-green part of the spectrum is reduced because the photopigments that mediate discrimination in this range are abnormally similar. Whereas normal subjects have pigments whose wavelengths of peak sensitivity differ by about 30 nm, the peak wavelengths for protanomalous observers are thought to differ by only a few nanometers. We found, however, that although this difference occurred in some protanomalous subjects, others had pigments whose peak wavelengths were identical. Genetic and psychophysical results from the latter class indicated that limited red-green discrimination can be achieved with pigments that have the same peak wavelength sensitivity and that differ only in optical density. A single amino acid substitution was correlated with trichromacy in these subjects, suggesting that differences in pigment sequence may regulate the optical density of the cone.

Amino Acid Substitution↗

[Acquired disorders of color vision].

This article is a general view of acquired disorders of color vision. The revision of the best known methods and of the etiopathogenic classification is not very important in ophthalmology but on the other hand, the detection of the blue defect advertise and associated ocular pathology. There is a major interest in serious diseases as multiple sclerosis, AIDS, diabetes melitus, when the first ocular sign can be a defect in the color vision.

Color Perception Tests↗

Inheritance of color vision in a New World monkey (Saimiri sciureus).

Squirrel monkeys (Saimiri sciureus) have a striking color-vision polymorphism; each animal has one of six different types of color vision. These arise from individual variation in the presence of three different middle- to long-wavelength cone pigments. The distribution of cone phenotypes was established for a large sample of squirrel monkeys, including several families, through analysis of a retinal gross potential. The results indicate that the inheritance of color vision in the squirrel monkey can be explained by assuming that the three middle- to long-wavelength cone pigments are specified by three alleles at a single locus on the X chromosome. This arrangement is discretely different from that found in Old World monkeys and humans.

Animals↗

Color vision and occupational chemical exposures: I. An overview of tests and effects.

The paper presents a summary of the literature published until December 2000 on effects from some industrial chemical exposures on color perception, as well as short descriptions of the tests applied. Several different tests have been used to study acquired alterations of color vision. These changes are frequently found in the blue-yellow axis. Many of the tests were originally designed to detect congenital alterations in the red-green axis, and thus have relatively low sensitivity when studying chemically induced deficits in color perception. At present, the Lanthony D15-desaturated panel seems most suitable for application in industrial settings, since it is clearly the most sensitive and easily administered test. Color vision seems to be a physiological function very sensitive to several chemicals. The potency of industrial chemicals to induce color vision deficiencies has often been investigated during the last two decades. The chemicals most frequently studied are different solvents and mercury. Pronounced effects on color perception have been reported following chronic exposure to organic solvents such as styrene, carbon disulphide, perchloroethylene, n-hexane and solvent mixtures, and to organic as well as inorganic mercury. The effect of occupational toluene exposure seems not as well established, since only slight effects and several negative studies have been reported. For some of these compounds the effect on color vision has been further established through the finding of clear dose-effect relationships. In a few cases, even acute exposure situations, e.g. exposure to toluene for a few hours or acute alcohol intake, seem to affect color perception. Follow-up studies are needed to investigate the possible reversibility of effects in relation to discontinued or reduced exposures.

Color Perception Tests↗

[The examination of color vision using a 2 metameric equation method].

Modern anomaloscopes with four independent light channels (i.e. Besançon-Anomalometer which was presented in 1979 at the SFO Congress) allow accurate examinations of color vision. In our routine clinical examination, we use two metameric equations: the red-green Rayleigh equation and the blue-green Moreland equation. This so called Two-Equation-Method enables the diagnosis of congenital and acquired color vision defects in a precise qualitative as well as quantitative way. For both equations the goal of the examination is to measure the absolute matching range. Abnormal color vision is diagnosed if the absolute matching range is shifted and/or enlarged in one or both of the two metameric equations. In congenital colour vision deficiencies, the results are similar to those obtained with the Nagel anomaloscop. The different types of acquired defects are compared with the types of Verriest's classification. A computer controlled clinical examination of color vision, which will make the procedure simplier and shorter for the patient is actually being developed.

Color Perception↗

Color vision defect type and spatial vision in the optic neuritis treatment trial.

PURPOSE: To describe the types of color vision defects present in the acute phase of the disease and 6 months into recovery in the 438 participants of the Optic Neuritis Treatment Trial. METHODS: Patients meeting strict eligibility criteria were seen within 8 days of the onset of symptoms and then at regular follow-up visits. At the first and 6-month visits (and subsequent annual visits), spatial vision (acuity, contrast sensitivity), visual fields, and color vision were measured. Farnsworth-Munsell 100-hue tests were scored by a variant of the method of quadrant analysis described by Smith et al (Am J Ophthalmol. 1985; 100:176-182). RESULTS: Most persons show mixed red-green (RG) and blue-yellow (BY) color defects (one type predominating, accompanied by a lesser defect of the other type). BY defects tend to be slightly more common in the acute phase of the disease, with slightly more RG defects at 6 months. Persons may shift defect type over time. Defect type was not related to any of the spatial vision measures at either test time or to treatment group; however, severity of color defect was related to both spatial vision measures and treatment group. CONCLUSIONS: Contrary to common clinical wisdom, optic neuritis is not characterized by selective RG defects. Color defect type cannot be used for differential diagnosis of optic neuritis.

Acute Disease↗

Changes of color vision in ocular hypertension.

Fifty-six ocular hypertension (OHT) patients were examined for 2-3 days in the Eye Clinic of Kuopio University Hospital. No glaucomatous changes were found. Twenty-seven of them were found to have several risk factors for developing glaucoma and medication was started. Twenty-nine of the patients did not show risk factors and had no medication. Color vision was examined with the Farnsworth-Munsell 100 (FM 100) hue test and Besançon anomalometer, later Color Vision Meter 712 at the beginning of the study and 3 years later. None of the 56 patients showed any glaucomatous changes after 3 years of the study. In the treatment group, the FM 100 test showed significantly (paired t-test, p = 0.004) improved error scores after 3 years. In the non-treatment group, 19 patients did not develop risk factors; they had no significant changes in the color vision results. In 10 patients of the non-treatment group, risk factors had developed with elevated intraocular pressure and medication was started for them after 3 years. Their color vision results in the blue anomalous quotient (AQ) of the anomalometer had significantly shifted to the blue part of the equation (paired t-test, p = 0.04). The other color vision results had not changed significantly. The significantly improved FM 100 scores in the treatment group could mean, that the treatment has a beneficial effect for the OHT eyes at risk for developing glaucoma.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Validity of clinical color vision tests for air traffic control.

BACKGROUND: An experiment on the relationship between aeromedical color vision screening test performance and performance on color-dependent tasks of Air Traffic Control Specialists (ATCS) was replicated to expand the database supporting the job-related validity of 13 FAA-accepted screening tests. METHODS: The original experiment (10) (n = 108), and the replication (n = 136) involved a total of 121 normal trichromats, 31 simple and 44 extreme anomalous trichromats, and 48 dichromats; both protans and deutans were included. The simulations of ATCS color tasks which served as validation criteria were flight progress strips (en route centers), aircraft lights and the Aviation Signal Light indicator (ATC terminal operations), and color weather radar (flight service station and en route center facilities). RESULTS: The validities (Kappa) of aeromedical screening tests ranged from 0.44 to 0.91 for prediction of error-free performance on all color-dependent tasks. CONCLUSIONS: The aeromedical screening tests were generally acceptable in terms of selecting individuals who did not make errors on ATCS color tests, but several tests had high false alarm rates. High job-related validity, in the vicinity of 0.90, was confirmed for several aeromedical color vision tests used for ATCS screening.

Adult↗

Color-vision polymorphism in wild capuchins (Cebus capucinus) and spider monkeys (Ateles geoffroyi) in Costa Rica.

New World monkeys are unique in exhibiting a color-vision polymorphism due to an allelic variation of the red-green visual pigment gene. This makes these monkeys excellent subjects for studying the adaptive evolution of the visual system from both molecular and ecological viewpoints. However, the allele frequencies of the pigments within a natural population have not been well investigated. As a first step toward understanding the relationship between vision and behavior, we conducted color-vision typing by analyzing fecal DNA from two wild groups of white-faced capuchin monkeys (Cebus capucinus) and one group of black-handed spider monkeys (Ateles geoffroyi) inhabiting Santa Rosa National Park of Costa Rica. All color-typed monkeys were individually identified. In C. capucinus and A. geoffroyi we found three and two pigment types, respectively, and the spectral mechanism that created one of the two Ateles pigments was found to be novel. In one Cebus group and the Ateles group, all alleles were present, whereas in the other Cebus group only two alleles were found, with one allele predominating. This was likely due to the effect of close inbreeding, indicating that wild populations can exhibit a variety of allele compositions. This result also suggests that the color-vision polymorphism can be easily distorted by natural factors, such as inbreeding, skewing the population structure.

Animals↗

Detection of congenital color vision defects using heteroduplex-SSCP analysis.

Gene deletion and hybrid gene formation result in congenital red and green color vision defects. The innumerable variations in these defects require the development of appropriate methods for detailed investigation. We used heteroduplex-single-strand conformation polymorphism (SSCP) analysis to detect the gene variations in subjects with congenital red and green color vision defects. For comparison, we also used polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) to detect these defects. In all 13 protan and 9 of the 15 deutan subjects, defects of the red or green pigment gene could be identified by either heteroduplex-SSCP or PCR-RFLP analysis. Through heteroduplex-SSCP analysis, sequence polymorphism was detected in exon 5 of the green pigment gene. One polymorphic sequence was present in 8 of 21 trichromats but in only one of 17 dichromats, showing a biased distribution. A specific variation was found in one protan by SSCP analysis. Heteroduplex-SSCP procedures are useful for objective clinical diagnostic testing and for further study of color vision variations because of their simplicity and reliability and because they provide more information.

Blotting, Southern↗

Acquired color vision loss and a possible mechanism of ganglion cell death in glaucoma.

PURPOSE: First, to study the cellular mechanisms of acquired color vision loss in retinal detachment and diabetic retinopathy. Second, to learn why, in glaucoma, the type of color vision deficit that is observed is more characteristic of a retinal injury than it is of an optic neuropathy. Third, to test a hypothesis of photoreceptor-induced, ganglion cell death in glaucoma. METHODS: Various histologic techniques were employed to distinguish the L/M-cones (long/medium wavelength-sensitive cones, or red/green sensitive cones) from the S-cones (short wavelength-sensitive cones, or blue sensitive cones) in humans and monkeys with retinal detachment, humans with diabetic retinopathy, and both humans and monkeys with glaucoma. To test if the photoreceptors were contributing to ganglion cell death, laser photocoagulation was used in a experimental model of glaucoma to focally eliminate the photoreceptors. As a control, optic nerve transection was done following retinal laser photocoagulation in one animal. RESULTS: Selective and widespread loss of the S-cones was found in retinal detachment as well as diabetic retinopathy. By contrast, in human as well as experimental glaucoma, marked swelling of the L/M-cones was the predominant histopathologic feature. Retinal laser photocoagulation followed by experimental glaucoma resulted in selective protection of ganglion cells overlying the laser spots. This was not seen with retinal laser photocoagulation by optic nerve transection. CONCLUSIONS: In retinal detachment and diabetic retinopathy, acquired tritan-like color vision loss could be caused, or contributed to, by selective loss of the S-cones. Both L- and M-cones are affected in glaucoma, which is also consistent with a tritan-like deficit. Although not a therapeutic option, protection of ganglion cells by retinal laser in experimental glaucoma is consistent with an hypothesis of anterograde, photoreceptor-induced, ganglion cell death.

Adult↗

A perspective on color vision in platyrrhine monkeys.

Studies carried out over the past two decades show that many platyrrhine (New World) monkeys have polymorphic color vision. This condition results from the sorting of allelic versions of X-chromosome cone opsin genes at a single gene site, yielding a mixture of dichromatic and trichromatic phenotypes in the population. Two genera of platyrrhine monkey are known to deviate significantly from this pattern. Examination of color vision, photopigments, and photopigment genes of all of these monkeys have stimulated a renewed interest in understanding the evolution of primate color vision.

Animals↗