Daltonism


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Daltonism

 

partial color blindness, one of the forms of color vision disturbance. Daltonism was first described in 1794 by J. Dalton, who himself suffered from this condition.

Daltonism is found in 8 percent of all males and 0.5 percent of all females. It is postulated that there are three elements in the retina, each of which is sensitive to only one of the three basic colors (red, green, and blue-violet). Various mixtures of these basic colors produce all shades perceived by the normal eye. This is normal, so-called trichromatic color perception. When one of these three elements is lacking, partial color blindness, or dichromatism, results. Persons suffering from dichromatism distinguish colors mainly by their brightness; qualitatively they are capable of merely distinguishing the “warm” tones of the spectrum (red, orange, and yellow) from the “cold” tones (green, blue, and violet). Among di-chromats one may distinguish between those with red blindness (protanopia), in whom the perceived spectrum is shortened at the red end, and those with green blindness (deuteranopia). In protanopia (Daltonism proper), red is perceived as being darker, and is confused with dark-green and dark-brown; while green is confused with light-gray, light-yellow, and light-brown. In deuteranopia green is confused with light-orange and light-pink, while red is confused with light-green and light-brown. Blue blindness, or tritanopia, is found extremely rarely and has no practical significance. In tritanopia all colors of the spectrum are represented as shades of red or green. In some cases there is simply a weakening of color perception—protanomaly (weakening of red perception) and deuteranomaly (weakening of green perception). All forms of congenital color blindness are hereditary. Women are carriers of this pathological inheritance; they themselves retain normal vision and are color blind only when they have a color-blind father and a mother who is at least heterozygous for that gene.

Acquired disturbances of color vision may arise with various diseases of the eyes and the central nervous system; one or both eyes may be affected and often for all the basic colors. Disturbances of color vision are diagnosed by means of special tables or spectral instruments. Testing of color vision is of great significance in the occupational selection of persons for work in transport, aviation, and marine jobs and in the chemical, printing, textile, and other branches of industry. Daltonism is not subject to treatment.

REFERENCES

Averbakh, M. I. “Tsvetooshchushchenie i ego rasstroistva.” In Oftal’mologicheskie ocherki. Moscow, 1949.
Kravkov, S. V. Glaz i ego rabota, 4th ed. Moscow-Leningrad, 1950.
Rabkin, E. B. Polikhromalicheskie tablitsy dlia issledovaniia isvetooshchushcheniia, 8th ed. Moscow, 1965.

M. L. KRASNOV

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