Color blindness- partial color blindness, a type of color vision disorder.
Color blindness was first described in 1794 by J. Dalton, who himself suffered from this shortcoming. Color blindness occurs in 8% of men and in 0.5% of women. In the central part of the human retina, there are color-sensitive nerve cells called “cones”. They contain three types of color sensitive pigments of protein origin. One type of pigment is sensitive to red, the other to green, and the third to blue. More precisely, they are sensitive to the wavelength corresponding to red, green and blue in our understanding. The vision of all the colors of the world is ensured by the “folding” of these three colors in our brain. In humans, the peak of sensitivity of these pigments is at a wavelength of 552-557 nm for red, 530 nm for green and 426 nm for blue. This is a normal, trichromatic color perception. With the loss of one of these elements comes partial color blindness - dichromasia. Persons suffering from dichromasia, distinguish colors mainly by their brightness; qualitatively, they are able to distinguish in the spectrum only “warm” tones (red, orange, yellow) from “cold” tones (green,blue, purple). Color blind on one color and people with low color vision perceive the colors of the world around them differently than we do, but often do not notice their difference from others. This happens because the color blind from childhood learn to call the colors of everyday objects generally accepted notation. They hear and remember that the grass is green, the sky is blue, the blood is red. In addition, they retain the ability to distinguish colors according to the degree of lightness.
Among dichromats, there are blind to red color (protanopia), in which the perceived spectrum is shortened from the red end, and blind to green color (deuteranopia). When protanopii, red color is perceived as darker, mixed with dark green, dark brown, and green - with light gray, light yellow, light brown. When deuteranopii green mixed with light orange, light pink, and red - with light green, light brown. Blindness to the violet color is tritanopia, it is extremely rare and has no practical value. In tritanopia, all the colors of the spectrum are represented by shades of red or green.In some cases, there is only a weakening of color sensation - protanomaliy (weakening of red color perception) and deuteranomaly (weakening of green color perception).
All forms of congenital color blindness are hereditary. Women are the vehicle of this pathological heredity; they themselves maintain normal vision and turn out to be color blind only when they have a color blind father along with at least a mother who is heterozygous for this gene.
Acquired color vision disorders can occur with various diseases of the organ of vision and the central nervous system; one or both eyes are affected and often all primary colors. Disorders of color vision are detected with the help of special tables or spectral instruments.