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At least 343 records · Page 19Linked to original sources
PubMed1996

Colour contrast thresholds in congenital colour defectives.

The influence of congenital colour defects on a clinical computer test for equiluminous colour discrimination is studied. Differences in relative spectral sensitivity and changes in colour contrast discrimination are two distinct manifestations of the abnormal genes responsible for congenital red-green defects. The very simple and rapid method of the heterochromatic flicker brightness test acts like an anomaloscope and can be used to distinguish protan and deuteran defectives. The depth of the congenital colour defect can be quantified by the colour contrast threshold measured in equiluminous conditions along a single red-green axis identical for all types of red-green colour defectives. Colour contrast thresholds in tritan colour axes are not influenced by congenital red-green defects and therefore they are of extreme clinical interest to detect and quantify acquired colour defects, even in the presence of a previously unknown congenital red-green defect.

Color Perception Tests↗
PubMed1980

The 1976 accident experience of civilian pilots with static physical defects.

The 1974 and 1975 aircraft accident experiences of civilian pilots with eight selected static physical defects have been examined and reorted previously. Three categories--blindness or absence of either eye, deficient color vision with a waiver, and deficient distant vision--had significantly more accidents than were expected on the basis of observed-to-expected ratios. In 1975, accident rates were calculated. The rates for air men with blindness or absence of an eye were still found to be significantly higher. Observed-to-expected ratios for 1976 were 1.91 for deficient color vision with a waiver, 1.28 for contact lens users, 1.37 for blindness or absence of either eye, and 1.62 for deficient distant vision. The accident rates per 100,000 h of cumulative and last 6 months' flying experience were significantly greater for contact lens users and monocular pilots than for the active airman population. The other groups had no consistently significant differences.

Accidents, Aviation↗
PubMedDate not supplied

Vision screening in a national sample of 11-year-old children.

This report describes the results of vision screening carried out by local health authorities on a national sample of 11-year-old schoolchildren using a standard Snellen chart. Of the 12 772 children tested, 78% had an unaided distant visual acuity of 6/6 or better in both eyes (optimal vision), 10% had a distant visual acuity of 6/9 in the worse or both eyes (near-optimal vision) and 12% had a visual acuity of 6/12 or worse in one or both eyes eyes (definite visual defect). In addition, near visual acuity was tested for 12 737 children and 5% were found to have defective near vision. Glasses had been prescribed for current use in 12% of children but a quarter of those prescribed glasses did not have them available at the time of the test. Testing revealed that 22% of children whose glasses were available had optimal or near-optimal unaided distant vision, the number increasing to 98% when retested wearing glasses. In contrast, 43% of the children who were without their glasses had optimal or near-optimal vision; 27% had a bilateral defect. Amongst the children for whom glasses had not been prescribed 4-6% had a visual defect. A higher proportion of children from non-manual family background than from manual family background had visual impairment and had been prescribed glasses, but there was no significant social class difference amongst the children with visual defects for whom no glasses had been prescribed. A defect of red/green colour vision was recorded in 6% of boys and 1% of girls. The proportion of children with poor visual acuity was similar in the group of children with defective colour vision and the group with normal colour vision.

Child↗
PubMed1987

An averaging method for the interpretation of the Farnsworth-Munsell 100-Hue Test--II. Colour vision defects acquired in diabetic retinopathy.

The Farnsworth-Munsell 100-Hue test is frequently used to assess acquired colour vision defects. In diabetic retinopathy the acquired defect is a mild or severe type III (Tritan) defect which may be coupled with poor overall hue discrimination. In consequence, error scores are often high and the 100-Hue polar diagram is difficult to interpret. In this study the averaging method of analysis proposed by Dain and Birch is used to examine 120 100-Hue plots obtained by patients with proliferative diabetic retinopathy. These plots have either moderate (150-300) or high error scores (greater than 300). The method of analysis is found to be effective in determining whether a Tritan defect is present or not.

Adult↗
PubMed1984

Empirical detection of congenital dyschromatopsia by electroretinography.

The electroretinographic rapid off-response, composed mainly of the late receptor potential of cones, is found to be abnormal in all protans and deutans so far tested. The rapid off-response can thus be used as an objective measure in the diagnosis of congenital red-green colour defect.

Adolescent↗
PubMed1993

Application of the spatiochromatic visual evoked potential to detection of congenital and acquired color-vision deficiencies.

Visual evoked potentials were recorded in response to spatiochromatic stimuli modulated in different directions in cone-activation color space from subjects with congenital and acquired color defects. This technique was effective for detection and classification of both mild and severe forms of congenital deficits. Results suggest that the visual evoked potential is useful for early identification of color abnormalities in acquired deficits such as diabetes and that it is sensitive enough to detect regional retinal losses of sensitivity (e.g., as in central serous choroidopathy). The spatiochromatic visual evoked potential provides a systematic and sensitive indication of different color-vision anomalies.

Adult↗
PubMedDate not supplied

Number and variations of the red and green visual pigment genes in Japanese men with normal color vision.

PURPOSE: We analyzed the red/green visual pigment genes in color-normal Japanese men to understand the relationship between color anomalies and genetic defects. METHODS: DNA from 120 color-normal Japanese men was subjected to polymerase chain reaction (PCR)-amplification for exons 2-5 of the red/green visual pigment genes and the PCR products were sequenced. The red:green gene ratios were estimated from the sequencing electropherograms of exon 5 and also from MvaI-restriction fragment analysis of the same exon. The first gene and the downstream genes in the pigment gene array were separately analyzed by PCR, direct sequencing, and/or single-strand conformation polymorphisms. RESULTS: The red:green gene ratios estimated from the ratios of peak heights of nucleotides on the sequencing electropherograms coincided with those estimated from the MvaI-restriction fragment analysis. Among the subjects analyzed, they were 1:1 in 43% (n = 52), 1:2 in 41% (n = 49), 1:3 in 6% (n = 7), and 1:>3 in 9% (n = 11). The first gene in the pigment gene arrays was red in all subjects. Only 1 subject (N22) had a green-red hybrid gene. Exons 2 and 4 had 2 haplotypes each, but exon 3 was highly polymorphic. Exon 5 of the green genes had one polymorphism at codon 283 with a frequency of 32%. CONCLUSIONS: The features of visual pigment genes in color-normal Japanese men were revealed. The data and establishing techniques may be useful for analyzing these genes in color-deficient subjects in the Japanese population.

Color Perception↗
PubMed1998

Computerized color perimetry in multiple sclerosis.

Color visual field analysis has proven highly sensitive for early visual impairments diagnosis in MS, yet it has never attained widespread popularity usually because the procedure is difficult to standardize, the devices are costly, and the test is fatiguing. We propose a computerized procedure running on standard PC, cost effective, clonable, and easy handled. Two hundred and sixty-four colored patches subtending 1 degree angle vision, with selected hues and low saturation levels are sequentially and randomly displayed on gray equiluminous background of the PC screen subtending 24 degrees x 40 degrees angle of vision. The subject is requested to press a switch at the perception of the stimulus. The output provides colored maps with quantitative information. Comparison between normals and a selected population of MS patients with no actual luminance visual field defects, showed high statistical difference.

Adolescent↗