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[Evaluation of the central visual field by the Friedmann Mark I analyzer and color vision in 85 patients with multiple sclerosis. Correlation with visual evoked potentials in 50 cases].

Analysis of the visual field using Friedmann's analyser Mark I and color study in 85 multiple sclerosis patients. Static perimetry of the central visual field and test batteries (Ishihara plates, 15 Hue Standard, 15 Hue of Lanthony) for acquired color vision defects were performed in 85 multiple sclerosis patients (61 definite, 12 probable, 12 possible cases). Results in patients were compared to data obtained in 53 control subjects matched for age. 64% of the 85 patients and 52% of 48 patients with no history of optic nevritis showed visual field abnormalities and/or color vision defects. Comparison with VEP was available in 50 patients. While 10 patients had abnormal VEP and normal static perimetry and coloration tests, 5 patients had the reverse findings.

Adolescent↗

Eye development: random precision in color vision.

In insect and vertebrate eyes, different types of color-detecting photoreceptors are randomly distributed throughout the retina. A recent study has provided important new insights into the developmental mechanisms that generate the retinal mosaic required for color vision.

Animals↗

Color vision loss among styrene-exposed workers neurotoxicological threshold assessment.

Styrene represents nowadays one of the most used organic solvent. The current exposure limit proposed for this chemical differs significantly from country to country: the Threshold Limit Value-Time Weighted Average (TLV-TWA) proposed by the American Conference of Governmental Industrial Hygienists (ACGIH) is 50 ppm while the German, Finnish and Swedish occupational exposure limit is 20 ppm. Nevertheless, effects on the nervous system were recently reported in workers exposed at TWA styrene levels below the current TLV. Neuro-optic pathways have been shown to be particularly vulnerable to organic solvent exposure. Analysis and measurements of visual functions can provide important information on early neurotoxic effects. Previous studies support the hypothesis that styrene exposure can induce a dose-dependent color vision loss. The aim of this study is to assess a threshold level below which no detectable effect occurs for color vision. We applied a sub-application of the change point problem in two-phase regression considering one phase as a constant line. In accordance with this model the maximum-likelihood technique was used as a method to examine the dose- effect relationship between external styrene exposure and chromatic discrimination. The present article presents a joint analysis of data from two previously published studies, one carried out in Canada and the other in Italy. The age and seniority of the workers from both countries were remarkably similar, as were the process type, the chemicals used and the work-tasks of exposed subjects. The mathematical method presented here shows the existence of a statistically significant threshold. This finding shows that, in fiberglass-reinforced plastics industry, visual color impairment could be significantly detected above 4 ppm (upper limit of the confidence interval at 5% = 26 ppm). The exact clinical meaning of this effect, and also the progress of the impairment in exposed workers, is still to be assessed in further studies. The results of our study support the need of a reduction of the occupational limits for styrene in workplaces to values close to or lower than German, Finnish or Swedish exposure limits.

Adult↗

[Theoretical patterns of the panel D-15 test in congenital dichromatic color vision defects].

In order to study the theoretical patterns of the panel D-15 test for congenital dichromatic color vision defects, the spectral reflectance for the 16 color caps of the panel D-15 test was measured with a spectro-photometer. Then, the chromaticity-coordinates of each color cap were calculated using the spectral distribution of standard illuminant C. The theoretical patterns of the panel D-15 test for dichromats were obtained based on the confusion lines. For this procedure, the slope of the line between the color cap and the convergence point on the CIE chromaticity diagram was obtained first. Then, the order of the arrangement was decided starting with the slope having the smallest cap number and continuing progressively. For the chromaticity coordinates of the convergence points the following values were used; x = 0.7465, y = 0.2535 for protanopia, x = 1.08, y = -0.08, x = 1.40, y = -0.40, and x = 1.70, y = -0.70 for deuteranopia, and x = 0.171, y = 0.000 for tritanopia. The results show a very clear similarity between the orientation axis obtained by simulation and the actual data. Therefore, it was confirmed that dichromats arrange the color caps in the order of the slope of the line between the color cap and the convergence point, when performing the panel D-15 test. Furthermore, it was suggested that the patterns of the panel D-15 test differ by the convergence points among dichromats even of the same type.

Color Perception↗

The genes for color vision.

Three centuries of experimentation in optics, psychophysics and biochemistry established the dependence of color vision on three kinds of light-absorbing molecules, or pigments, in the cone cells of the retina. The author has isolated the genes that encode the pigments and has identified genetic anomalies that lead to color blindness.

Animals↗

Color vision and age in a normal North American population.

Color vision is known to change with age. We conducted the Farnsworth-Munsell (FM) 100-Hue and the Lanthony Desaturated Panel D-15 (DD-15) tests in 115 normal North American subjects aged 5-81 years to obtain age-specific norms for these procedures. For each test, color discrimination was best between the ages of 20 and 50 years. Both increasing age and the occurrence of lens changes were significantly associated with increasing 100-Hue error scores. Age-specific norms for the 100-Hue test were comparable with those obtained by Verriest in a European population, but such norms for the DD-15 test are problematic. Our data indicate somewhat greater variability in the DD-15 than in the 100-Hue test.

Adolescent↗

Color vision screening and viewing conditions: the problem of misdiagnosis.

The most popular techniques for assessing color vision, the pseudoisochromatic tests, have been found to differ widely in their sensitivity to changes in viewing conditions. A significant number of color-normal subjects will be misdiagnosed as color defective by some of the standard tests with even relatively minor variations from standardized viewing conditions. These results appear to have strong implications for the use of the tests in many applied settings which precise control over viewing conditions is difficult. In particular, as the consequences of a misdiagnosis become very serious, the tests must be used with special caution. If we were to recommend one test for use, our findings point to the Ishihara, which appears impervious to variation in viewing conditions.

Color Perception Tests↗