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Results for “Color Vision Defects”

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At least 361 records · Page 20Linked to original sources
PubMed1984

The effect of restricted viewing time on the performance of colour defectives using the City University Colour Vision Test.

The effect of restricting viewing time to 3.75 ms on the performance of seven red/green colour defectives is studied using the City University Colour Vision Test. One further subject who was screened as colour-defective but not classified on the City plates was studied in the same way and results for this subject are presented separately. The results are compared to those for normal observers who exhibit a tritan-classified defect when viewing time is restricted to 3.75 ms.

Color Perception Tests↗
PubMed1978

Blue cone function in a family with an inherited tritan defect, tested with electroretinography and psychophysics.

The sensitivity of the blue cone system to low frequency flicker was tested with a psychophysical and an electroretinographical method. With the psychophysical method the subjects, members of a family with an inherited tritan defect, showed no sign of the presence of the blue cone system. With the electroretinogram the sensitivity was also significantly lower than in normal subjects, thus indicating a retinal origin of the tritan defect.

Adolescent↗
PubMed1976

New data on the vision of South American Indians.

A total of 466 males and 437 females from four Brazilian Indian tribes were tested for color blindness with Ishihara's plates. Defective persons were found in three of the four tribes, but when these and other groups are considered the evidence suggests that the frequency of this trait is lower among Amerindians than among Caucasian populations. Visual acuity tests were performed on 296 Yanomama Indians. Their visual acuity was apparently not as sharp as that of the Cayapo or Xavante. But the scarcity among the Yanomama of persons with serious visual impairment of subcutaneous nodules suggests that the focus of onchocerciasis discovered among them is of recent origin.

Adolescent↗
PubMed2002

Colour blindness in Italian art high school students.

To highlight the link between colour blindness and school achievement, the Ishihara and Farnsworth tests were administered to 3,565 high school art students (2,545 girls and 1,020 boys). Analysis showed colour defective students were discriminated against in theoretical subject matter, relative to orthochromate students, but not in the art-related subjects. This emphasizes the need to recognize youth with colour defective vision early.

Adolescent↗
PubMedDate not supplied

[The pathogenesis of diabetic dyschromatopsia].

Essential data about the physiology of colour vision are reminded, with a stress layed on the possible contribution of the rodes in perception of blue and green colours. The main features of the diabetic dyschromatopsia are reviewed, together with their pathomorphological support and the two existing theories regarding its pathogenesis: vascular origin versus neuronal origin of the defect. The contribution of the photocoagulation to these alterations is also discussed.

Animals↗
PubMed1994

Computerized colour vision testing.

There are many advantages to the computerization of colour vision tests. However, previous computerized colour vision tests have involved equipment and methods not commonly used in clinical practice. We created computer emulations of the City University Colour Vision Test (CUT), Ishihara plates and American Optical Hardy-Rand-Rittler (AO-HRR) plates using a commonly available 24-bit colour Macintosh computer. Our colour monitor was calibrated to standard display white (D65), and colour plates were imaged with a colour scanner. The computerized colour images were compared with the standard test plates in a sample of 21 subjects with normal colour vision, 10 patients with congenital red-green defect and 1 patient with an acquired mixed colour defect. The computer images of the three tests correlated well with their conventional counterparts on kappa statistic analysis (p < 0.001), for both the colour normal and colour defective groups. We conclude that our computer emulations of the CUT, Ishihara and AO-HRR tests screen subjects with normal colour vision with high specificity and delineate congenital colour defects with a sensitivity comparable to that of their conventional counterparts.

Adult↗
PubMed1976

Unilateral colour vision defect resembling tritanopia.

A case of unilateral tritan defect is described. Colour-naming experiments showed that the tritanopic eye could perceive multiple colour hues. Although the defect resembled congenital tritanopia, it was considered to be acquired secondary to retinal pathology.

Adult↗
PubMed1995

[Ocular findings in Desferal therapy].

Desferrioxamine (DFO) is the most important drug in the treatment of thalassemia major and other hematological diseases requiring regular transfusion. It eliminates excessive ferritin by building up chelate complexes. Different mechanisms of possible DFO toxicity are induction of oxidation, damage of the blood-retina barrier, or reduction in other metalloions (Cu2+, Zn2+). The objective of the present study was to evaluate the ocular side effects of DFO treatment. We prospectively examined 17 patients aged 5 to 25 years, all of them treated with DFO. Visual acuity, pupillary reaction, anterior segment, lens and fundus were checked. If possible, visual fields, color vision, dark adaptation, stereoscopic vision, and contrast sensitivity were investigated. Lens opacities were found in 41% (7/17), changes in the retinal pigment epithelium in 35% (6/17), tortuosity of retinal vessels in 24% (4/17), dilation and sheathing of the retinal vessels in 18% (3/17), defects in color vision in 29% (5/17), and abnormal dark adaptation in 18% (3/17) of the patients. The oculotoxicity of DFO is dose-dependent. Major side effects like depression of the visual acuity are partially reversible after discontinuing the therapy. Regular ophthalmological check-ups are therefore necessary.

Adolescent↗
PubMed1985

The genetics of tritan disturbances.

Tritan (blue-green) colour vision disturbances have been found in 79 individuals in six families, revealing an autosomal dominant mode of inheritance with a wide variability of test results within families. Evidence is presented that it is--in contradistinction to the X-chromosomally inherited red-green defects--incorrect to make a subdivision between dichromasia (tritanopia) and anomalous trichromasia (tritanomaly). On the basis of three small screening series, totalling 1900 individuals, the frequency of tritan disturbances is estimated to be around 2 per 1000. Seven males have been observed carrying both inherited tritan and red-green defects.

Adolescent↗
PubMed1982

Color in the dreams of the color-blind.

This paper attempts to illustrate how three color-blind patients utilized color in their dreams in such a manner as to actively deny their visual defect. These patients had displaced to the eyes some critical conflicts about other body parts. The use of color to deny color blindness thus further served to deny other physical defects, both real and imaginary. In addition, this defense helped to fend off intense affects related to these defects as well as associated castration anxieties.

Adult↗
PubMed1989

Effects of viewing conditions on standard measures of acquired and congenital color defects.

We examined the effect of variations in viewing distance and viewing duration on the performance of color-normal observers with four standard tests of color vision. Significant effects of the experimental manipulations were obtained: both increasing viewing distance and decreasing viewing duration significantly increased the number of errors made by observers. Moreover, the four tests differed widely in their sensitivity to the variations in viewing conditions. Practical implications of the findings for the administration and selection of plate tests are discussed, and possible mechanisms underlying the results are suggested.

Color Perception↗
PubMed1990

Cone dystrophy and supernormal dark-adapted b-waves in the electroretinogram.

A male patient suffering from cone dystrophy was followed over 9 years. In addition to the typical clinical and electrophysiologic signs, supernormal b-waves were found in the dark-adapted electroretinogram. Our case is compared with 12 similar patients described in the literature. Our patient differed from the other patients in the following aspects: he was male and had a congenital stationary disease with a small pigment epithelial scar in the left eye only and no other fundus changes up to the age of 22 years. He did not complain of night blindness. The dark-adapted electroretinogram of our patient showed a normal b-wave threshold with increased b-wave amplitudes and markedly prolonged b-wave latencies and implicit times. This combination of signs has not been reported to date in any other patient and points towards a postreceptoral defect of the interneuronal connection.

Adolescent↗
PubMed1980

Evidence for an effect by colour defect on personality.

This paper discusses whether defective colour vision affects the type of personality of the individual. Three pieces of recent research are examined. Pickford and Cobb (1974) found a positive relation between colour defect and type of personality when they tested a sample of students in psychology. However, two later studies of school children did not demonstrate such a relationship. It is postulated that the contradiction in results between the first and the last two studies can be explained by the assumption that the effects of colour defect on the personality do not occur until later in life.

Adaptation, Psychological↗