Medical Encyclopedia

Color blindness

How does a person recognize colors?

At the refraction of sunlight through a prism we get a color spectrum (from red to violet). A red color corresponds the range of lengths of waves of 650-700 nm, and violet - 400 nm. Shorter (UV) and longer (infrared) waves the human eye cannot see. Visible light waves of different lengths a person perceives as different colors. All tints of spectrum can be got at mixing of three primary colors - red, green and violet.

Color sight of human is provided by retorts retinas which are located in the central fossula of retina (areas of maximal sharpness of sight). In retorts there are three types of colors perceiving element, everybody perceives one of three primary colors - green, red, violet. Every color has the length of light wave: violet - short light waves, green - middle waves, red - long waves. Different combinations of these colors form a various color gamut, which is perceived by a human eye. A human can distinguish colors only by the light. In darkness sight is provided by sticks retinas, capable only to distinguish the degree of luminosity. They are responsible for black-and-white sight.

What is color blindness?

Color blindness is violation of color sight, at a color-blindness a person does not distinguish colors.

Violations of color sight are subdivided into complete absence of color sight (color blindness, or monochromasia) and on so-called anomalies of color sight. Anomalous trichromatic sight, when a color is sometimes determined correctly, sometimes - wrongly. Deuteranomaly is a deuteranomalopia, a protanomaly is partial blindness on a red color, rarer there are people with complete blindness to the green and red colors and very rarely there is absence of perception of violet color - tritanomaliya. At violation of color sight (color blindness) a sensitiveness to the red and green colors goes down or absents. At dichromatic deuteranopia a person does not see green color. At the simultaneous display of these two anomalies a person from color spectrum distinguishes only two colors: yellow - long light waves and dark blue - short. People with violations of color sight for distinction of colors is needed a large color saturation and more time. At different illumination they recognize the tints of one color as different colors.

Symptoms of color blindness

Color blindness

  • Fatigue that is caused by color irritants.
  • Confusing colors.

Color blindness test

Color blindness test is very simple. You can pass it right now. Look at the pictures of this article: if you will be able to recognize numbers on pictures, your color sight is in a norm. Test yourself - the faster you recognize the number, the better your color sight. color blindness test is very important for some professions and types of activity.

Causes of color blindness

Color blindness test

The inherited absence of perception of green or red color is related to X-chromosome. Complete color blindness more frequent is innate. It can be purchased and shows up considerably later because of degeneration of yellow spot.

Inability to recognize colors - color agnosia is related to the damage of center of sight in the the cerebral cortex.

Color blindness and profession

It is well-proven that patients with violations of color sight are the culprits of travelling incidents more not frequent, than other people. And all the same for the representatives of certain professions the correct differentiating of colors is obligatory, for example, to the machinists of trains, captains of ships, pilots, drivers, designers, chemists and others. For them passing color blindness test is obligatory.

Other articles on this topic:

Amblyopia

Anisocoria