Even if you have never met a person who is unable to distinguish any colors, it must be said that color blindness is a fairly common disease of our time. Among the inhabitants of the planet, not only people can be color blind. Many animals are "owners" of color blindness. For example, bulls are not at all familiar, and formidable predators like lions and tigers know only blue and green. Cats and dogs perceive colors in the same way. Walruses, whales and dolphins do not distinguish colors at all and see the world around them in black and white.
Why are not all colors visible to the eye?
The retina of the human eye is a complex, multifactorial tool of the organ of vision, which transforms the light stimulus and allows you to see the object in its exact form and with all shades of color. It is equipped with light-sensitive cones containing a pigment responsible for determining color. A person has three types of light sensors located on the retina of the eye, the so-called cones. Each contains a certain set of protein pigments. Speaking unscientifically, each of these cones is responsible for the perception of a certain color: red, green and blue. In the case when one of the set of protein pigments is missing, a person loses the ability to perceive a certain color. With the normal functioning of all three sensors, a person distinguishes about a million shades of color, but with two - only 10,000 (100 times less). Color blindness is a deviation from the norm when the work of at least one light sensor is disrupted.
Colorblind people have little or no color perception, but can recognize colors by brightness or by tones that are cold or warm. Colorblind people are not always aware of their disease and do not notice their differences in perception from the sensations of other people. Memory helps them with this. It is the memory and brightness of the image that allows them to judge a certain color and compare it with another palette.
Types of color blindness
Color blindness also has many varieties. Sometimes a person is born with less than three color cones. Hence the groups of people according to the perception of color:
Trichromats (normal, all three cones of protein pigments function in the retina of the eye).
Dichromates (only two cones function; there are problems with recognizing many shades).
It was this deviation that John Dalton, an English naturalist, identified in himself, and was the first to describe color blindness according to his own feelings from a scientific point of view. He just belonged to the group of dichromats, when red and green colors are seen as different. D. Dalton wrote his first work on color blindness at the end of the 18th century.
Monochromats (only one type of cones functions; in this case, a color blindness test will show that people do not know about colors, the whole world is black and white for them).
Anomalous trichromats
There are deviations in people whose retina is equipped with all three light sensors, and it would seem that all colors should be perceived. The problem may lie in the so-called color dips. The fact is that, ideally, the sensitivity zones of the light sensors of the eye, which are responsible for the perception of a certain color, should overlap each other, necessarily evenly. This makes it possible for the eye to perceive all the shades when moving from one color to another: from blue to green, from green to yellow, from yellow to orange and beyond. When the sensitivity zones shift (superimpose one on top of the other), they begin to argue, shades overlap, pure colors fade. The brain gets confused and starts to identify some colors as just grey. This is called abnormal tricolor vision.
Color blindness is congenital
Partial or complete inability to distinguish colors is a hereditary or acquired pathology (much less common).
Hereditary color blindness is a recessive trait of inheritance associated with the pathology of the X chromosome, so more often the disease is inherited from the mother by boys.
As you know, the female embryo is a carrier of two X chromosomes. But for normal color perception, one healthy X chromosome will be enough. For girls, the disease only spreads when both mother and father suffer from color blindness. But even in this case, according to the laws of genetics, color blindness in women who have only one chromosome with the affected gene, which does not appear in the carrier, can be inherited by the son. But that doesn't have to happen either. The gene for color blindness can be passed down even through several generations. Again, the male population is more often at risk.
According to statistics, color blindness in women is recorded only in 0.1% of cases. Among men, 8% are colorblind. With a hereditary factor, color blindness is, as a rule, a pathology of both eyes that does not progress over time.
Color blindness acquired
The main factors influencing the acquisition of color blindness are always directly or indirectly associated with either brain injuries or damage to the retina. Sometimes a concussion received in childhood can subsequently affect color perception. In addition to childhood trauma, other factors can also influence the acquisition of color blindness:
- Old age.
- Eye damage due to trauma.
- Concomitant eye diseases (glaucoma, cataract, etc.).
- Medications that have side effects.
Diagnosis of color blindness. Testing
Color blindness is a given that you just need to accept. He is not being treated. It's the same as an ear for music: some have it, some don't. Never self-diagnose. If you notice a deviation in the perception of color in yourself or your children, you need to contact a specialist. There are proven methods for determining color blindness and its type.
1. Rabkin's test (polychromatic tables).
The test for color blindness in this test is done by looking at tables that show various numbers or letters. Readable images are applied using color spots that are the same in contrast and brightness. The result of the test will be the ability of the subject to recognize the necessary numbers or letters in the images.
2. Ishihara test.
A similar test in the form of tables that allows you to more accurately determine the moderate, severe degree of color blindness and complete color blindness. There is a complete edition of this test with 38 tables. They are used by professional ophthalmologists.
An abbreviated version of 24 tables is used for express testing at municipal institutions, airports. There is also a short specialized edition of 10 tables for preschoolers and illiterate people. Instead of letters and numbers in these tables, images of geometric shapes and various lines are used.
Color blindness and human profession
The limitations that may be associated with the choice of a profession for a color blind person are very important. First of all, these restrictions apply to professions where there is responsibility for life, one's own or other people's. Color-blind people are not accepted for military service, they cannot be pilots of aircraft, drivers of commercial vehicles and chemists. For these professions, annual medical examinations are mandatory, which are admission to. If a person has color blindness during the examination, his rights in the profession are sharply reduced. He can engage in theoretical training of young professionals, perform office work related to his professional skills.
Color blindness and driver's license
If in some professions color blindness is a sentence, then for obtaining restrictions do not apply to all. The opinion of a specialist is important here.
Driving license and color blindness are quite compatible concepts, but only after the conclusion of an ophthalmologist. Only a doctor determines the type and degree of color blindness, and therefore issues permission to the patient to drive a private car. Color-blind people can get the rights of categories "A" and "B", in which there will necessarily be a mark "Without the right to work for hire."
Help for colorblind people
Scientists regularly offer new medical "gadgets" that can alleviate the plight of people with disabilities. It turns out that despite the fact that doctors cannot fix cone sensors, it has become possible to reprogram the brain to perceive color correctly. Today, special glasses have appeared, in which narrow spectral stripes are simply “cut out” by lenses and pure colors are separated from each other. The principle of contrast enhancement allows red, blue and green colors not to mix.
Science has helped many colorblind people see colors they didn't even know existed: purple, bright green, and bright red.
