Acquired color defects in patients with open-angle glaucoma and ocular hypertension.
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Color Perception Tests↗
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[The colour discrimination of colour-defective persons in a wide range of colour space].
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Color Perception↗
On a possible explanation of the unusually high rates of colour vision defects in some west of Scotland primary schools.
The rate of Colour Vision Defect in some West of Scotland Primary Schools can be nearly four times higher than the normal rate for European whites. Population isolates in Ireland at the time of the troubles when immigration to Scotland was occurring could be a possible explanation.
Child↗
Velhagen Pfügertrident pseudoisochromatic plates in screening congenital red-green vision defects.
Red-green colour vision defects were screened in a group of 425 trade school students using Velhagen Pflügertrident pseudoisochromatic plates. Thereafter, the students were examined with the Nagel anomaloscope. Of the 425 students, 31 (7.3%) were found to be colour defectives. Deuteranomalous defects were found in 4.9% of cases; deuteranopic defects, in 0.2%; and protanomalous defects, in 2.1%. There were no protanopic students in the study group. The Velhagen plates found 19 of the 31 defectives (sensitivity, 61.3%); none of the students with normal colour vision were suspected of being colour defectives (specificity, 100%). The sensitivity of the Velhagen plates is not as high as that of other pseudoisochromatic tests. However, the Velhagen Pflügertrident test is easy to use when screening of pre-school-aged children is needed.
Adolescent↗
Doctors and the assessment of blood glucose testing sticks: does colour blindness matter?
A group of doctors with congenital colour vision deficiency (CCVD) were compared with a group of controls in their assessment of colour blocks in the colour range of a widely available blood glucose testing stick. The majority of doctors with CCVD agreed with controls on colour matching. However, subjects with severe CCVD tended to match test blocks to a wider range of options than either those with a less severe defect or controls. This paper discusses the implications of these findings.
Adult↗
Dominant cone dystrophy starting with blue cone involvement.
The results of ophthalmological and colour vision studies are reported on 13 patients from a family with a dominant cone dystrophy spanning seven generations. The onset of visual deterioration occurred in the third or fourth decade. In the early stages of the disease, when visual acuity is still close to normal, a severe defect in the blue sensitivity is already present, as measured by spectral sensitivity curves and other tests suitable for the detection of tritan defects. In our opinion this condition represents a distinct entity with autosomal dominant inheritance.
Adult↗
Colour-blindness in Colombia.
The frequency of defective colour vision was studied in two neighbouring villages in the Andes Mountains of Colombia using AO H-R-R Pseudoisochromatic plates. The frequency of the red-green colour-blindness in males is almost the same in both villages (2.36-2.53%), being similar to frequencies reported for other mestizo' populations in Latin America. In one of the communities, families in which colour-blindness occurred were wealthier (P is less than 0.05) than non-colour-blind families, but there were no significant differences by colour vision class in numbers of surviving children nor mother's marriage age. These findings are consistent with the idea that in societies at the agricultural level, colour-blindness is selectively neutral. The association of colour-blindness with higher socio-economic status is expected given the history of European conquest in the New World, and suggests that the major cause of varying rates of the defect in Latin American populations is socio-economic heterogeneity and by inference different degrees of European-Amerindian admixture.
Age Factors↗
Familial appraisal of colorblindness in school children of an Indian population.
A total 2000 unrelated school children were screened for colorblindness in Vishakhapatnam, India. Whether the protan and deutan defects are the result of mutations at one locus or at two loci has not been completely resolved, although the evidence favors two discrete loci. The investigation was extended to the families of the 40 color vision anomalous children to study the descendance patterns of these two loci. The importance of these observations are discussed.
Adolescent↗
[Acquired colour-vision-deficiencies caused by side-effects of pharmacotherapy (author's transl)].
Acquired colour-vision deficiencies are an early indicator for drug-induced retinopathy as well as drug-induced retrobulbar neuritis. Koellner's rule, which says, that damage of the retina induces a tritan-defect, and damage of the optic nerve induce a red-green-defect is also valid for defects secondary to drug-toxicity. Pseudoisochromatic plates, anomaloscope and other tests (Panel D-15-test) have to be selected correspondingly to use them as screening-methods.
Antipsychotic Agents↗
A consideration of the racial incidence of congenital dyschromats in males and females.
The female incidence of congenital dyschromats corresponds to the square of the males in the Northern European populations, but this relation is not always true in the non-white races. The above-mentioned facts in the non-white races which are theoretically strange are considered to be caused by an anti-glare factor of pigment epithelium in their eyes, on the assumption that the abnormal color sense of color defectives may be a special form of visual dysfunction glare pointed out by IINUMA.
Asian People↗
Similarities between congenital tritan defects and dominant optic-nerve atrophy: coincidence or identity?
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Adolescent↗
On the incidence of unilateral and bilateral colour blindness in heterozygous females.
In 303 mothers of colour-blind sons, both eyes were tested with pseudoisochromatic plates and with the anomaloscope. Two hundred thirty healthy normal and 56 colour-blind males served as controls. In good agreement with the expected proportion of homozygotes in our sample, 17 colour-blind mothers were detected. Eight others had difficulty reading pseudoisochromatic plates and were conspicuous at the anomaloscope. In these, both eyes were affected to a very similar, moderate degree. Monocular disturbances of colour vision were not observed in the entire series. Our data suggest that (1) in most (if not all) of the carriers with colour vision impairment, there is no complete lack of normal retina cones, and (2) the proportion of defective retina cones is remarkably similar in both eyes of individual heterozygotes. The latter observation may indicate that at the time of X-differentiation there is a common primordial cell pool for both retinas.
Adolescent↗
The UWCDot colour vision test and low vision.
PURPOSE: Previous studies have shown that colour vision defects are common in the low vision population even when properly designed tests are used. However, there are very few clinical tests available that are suitable for this group of patients. One of the more common is the Jumbo D-15 (JD15). Although this test uses caps more suitable for the reduced acuity, it requires the patient to have some knowledge of colour order and sufficient dexterity to manipulate the caps. We compared the JD15 with the University of Waterloo Colored Dot test (UWCDot), which has neither of these requirements, to determine whether the UWCDot test could be used as a substitute for the JD15. METHODS: The colour vision of 40 consecutive low vision patients was evaluated with both tests. Acuities ranged from 6/6 to 6/1600 with a median value of 6/30. RESULTS: All subjects could perform both tests. The kappa coefficient of agreement between tests was high at 0.85 when any major crossing was a failure on the JD15 and any mistake was a failure on the UWCDot. Classification of the type of defect was also reasonable when the defect was relatively severe. CONCLUSIONS: The UWCDot can be used as a substitute for the JD15 in the low vision clinic. Both tests identify individuals with moderate-to-severe deficiencies, but the UWCDot does not require any manual dexterity and it does not require knowledge of colour-order.
Adolescent↗
Congenital color blindness.
The term "color blind" is encountered frequently in areas pertaining to health, commerce, art, and entertainment, but in these cases it is generally not appropriate. Complete color blindness or achromasy is rare, but weakness or absence of discrimination to certain colors can be found in at least 8% of the male population. The most useful description of these color defects is in terms of hue and saturation, thresholds of which can be plotted as polar coordinates on a circular diagram. Plotting color thresholds with the chromagraph reveals more clearly than other clinical systems the true nature of color defects, as well as some inconsistencies in the traditional terminology and test methods. Fifty strongly color-defective subjects were tested by five different methods and the results compared. Normal values are also indicated.
Color Perception Tests↗
An A-71C substitution in a green gene at the second position in the red/green visual-pigment gene array is associated with deutan color-vision deficiency.
We studied 247 Japanese males with congenital deutan color-vision deficiency and found that 37 subjects (15.0%) had a normal genotype of a single red gene followed by a green gene(s). Two of them had missense mutations in the green gene(s), but the other 35 subjects had no mutations in either the exons or their flanking introns. However, 32 of the 35 subjects, including all 8 subjects with pigment-color defect, a special category of deuteranomaly, had a nucleotide substitution, A-71C, in the promoter of a green gene at the second position in the red/green visual-pigment gene array. Although the -71C substitution was also present in color-normal Japanese males at a frequency of 24.3%, it was never at the second position but always found further downstream. The substitution was found in 19.4% of Chinese males and 7.7% of Thai males but rarely in Caucasians or African Americans. These results suggest that the A-71C substitution in the green gene at the second position is closely associated with deutan color-vision deficiency. In Japanese and presumably other Asian populations further downstream genes with -71C comprise a reservoir of the visual-pigment genes that cause deutan color-vision deficiency by unequal crossing over between the intergenic regions.
Asian People↗
The influence of selected light intensities on color perception within the color range of natural teeth.
A study was undertaken to evaluate the influence of light intensity on the ability to discriminate color differences within the color range of natural teeth. The results show that shade selection is not significantly affected within the range of 75 to 300 fc. Neither the specialty of the dentist nor the amount of time in practice appeared to be a factor in making color discriminations. However, 7 of the 50 dentists serving as subjects were found to be color defective, and a difference was found between their color discrimination abilities and those of normal persons. This suggests that color-defective dentists should obtain assistance when matching tooth shades.
Color↗
Assessment of children's colour vision using the Pickford-Nicolson anomaloscope.
The colour vision of 439 boys, aged 4-11 years, was measured by the Pickford-Nicolson anomaloscope and four pseudoisochromatic tests. Matching range and dispersion of mid match point were found to be larger than adult values, but did not decrease with age. However, younger children took longer to establish matching range. Twenty-eight (6.4%) colour defectives were found and it is concluded that the Pickford-Nicolson anomaloscope gives valid results with children.
Age Factors↗
A simple eyesight screening programme for dental undergraduates: results after 7 years.
This paper reports the results of a simple eyesight screening programme for dental undergraduates which has been used for 7 years. Examinations were performed by orthoptists at a general hospital associated with the dental school. Defects in visual acuity, squints, limitations of convergence, defective stereopsis and colour vision were found. Many students were unaware of their visual defects, and the findings support the continued use of visual screening to identify and encourage those with defects to seek professional treatment at an early opportunity. Many of the defects were correctable or could be improved with help. Those with defective colour-vision were encouraged to seek assistance with shade selection during their clinical careers. The value of visual screening and the significance of the findings are discussed.
Color Vision Defects↗