Even if you have never met a person unable to distinguish any colors, you need to say that color blindness is a fairly common disease of our time. Among the inhabitants of the planet colorblind can be not only people. Many animals are "owners" of color blindness. For example, bulls are not at all familiar with red, and threatening predators, like lions and tigers, only know blue and green. Similarly perceive the color gamut of a cat and a dog. Walruses, whales and dolphins do not distinguish colors in general and see the world around them in black and white.
Why not all colors are available to the eye?
The retina of the human eye is a complex, multifactorial instrument of the organ of vision that converts a light stimulus and allows you to see an object in its exact form and with all the shades of color. It is equipped with photosensitive cones containing a pigment responsible for determining the color. A person has three types of light sensors located on the retina of the eye, the so-called cones. In each - a certain set of protein pigments. If to speak with unscientific language, each of these cones is responsible for the perception of a certain color: red, green and blue shades. In the case where 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 discerns 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 even one light sensor is disrupted.
People with color blindness, almost do not perceive shades, but can recognize colors by brightness or by tone, cold or warm. Color blinds do not always know about their disease and do not notice their differences in perception from the sensations of other people. In this they are helped by memory. 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 is also a variety of varieties. Sometimes a person has less than three color cones. Hence the groups of people on the perception of color:
• Trichromate( norm, all three cones of protein pigments function in the retina of the eye).
• Dichromates( only two cones are functioning, there are problems with recognizing many shades).
This deviation was determined by John Dalton, an English naturalist, and was the first to describe color blindness according to his own sensations from the scientific point of view. He just belonged to the group of dichromates, when the red and green colors are seen as different shades of brownish-yellow color. The first work on color blindness D. Dalton wrote at the end of the XVIII century.
• Monochromats( only one type of cone is functioning, in this case the color blindness test will show that people do not know about colors, the whole world is black and white for them).
Abnormal trichromate
There are deviations in people whose eye retina is equipped with all three light sensors, and it would seem that all colors should be perceived. The problem can be the so-called color failures. The point is that, ideally, the sensitivity zones of light sensors, the eyes responsible for the perception of a certain color, must overlap each other, necessarily evenly. This allows the eye to perceive all the shades in the transition from one color to another: from blue to green, from green to yellow, from yellow to orange and beyond. When the sensitivity zones shift( overlap one another), they begin to argue, the shades are layered, the pure colors fade. The brain becomes entangled and begins to identify certain colors as just gray. This is called an anomalous tricolor vision.
Color blindness congenital
Partial or total inability to distinguish colors is a hereditary or acquired pathology( it is much less common).
Hereditary daltonism is a recessive sign of inheritance, associated with the pathology of the X chromosome, so the disease is usually inherited from the mother by the boys.
It is known that the female embryo is the carrier of two X chromosomes. But for a normal color perception, one healthy X chromosome will suffice. The disease spreads to girls only in the case when both mother and father suffer from colorblindness. But in this case, according to the laws of genetics, color blindness in women who have only one chromosome with the affected gene, which has not manifested itself in the carrier, can inherit the son. But this does not necessarily happen. The gene for color blindness can be transmitted even after several generations. Again, the male population is more likely to enter the risk zone.
According to statistics, color blindness in women is recorded only in 0.1% of cases. Among the male colorblind 8%.With a hereditary factor, color blindness is, as a rule, a pathology of both eyes that does not progress with time.
Color blindness acquired by
The main factors affecting the acquisition of color blindness are always directly or indirectly related either to brain trauma or to damage to the retina of the eye. Sometimes the concussion obtained in childhood may subsequently affect the color perception. In addition to childhood injuries, other factors can influence the acquisition of color blindness:
- . Old age.
- Eye damage due to injury.
- Concomitant eye diseases( glaucoma, cataract, etc.).
- Drugs that have a side effect.
Diagnosis of color blindness. Testing
Color blindness is a reality that you just need to accept. He is not being treated. This is the same as a musical ear: someone has it, but someone does not. Never need to do self-diagnosis. If you notice a deviation in the perception of color in yourself or your children, you need to turn to a specialist. There are approved methods for determining color blindness and its type.
1. Rubkin's test( polychromatic tables).
The color blindness test in this test is done by looking at tables that show different numbers or letters. Readable images are applied with the help of color spots, the same in contrast and brightness. The result of the test will be the ability of the subject to find out in the images the desired numbers or letters.
2. Ishihara test.
Similar test in the form of tables, allowing more accurate determination of a moderate, strong degree of color blindness and complete color blindness. There is a complete edition of this test from 38 tables. They are used by professional ophthalmologists.
A shortened version of the 24 tables is used for rapid testing when hiring municipal institutions and airports. There is also a short specialized edition of 10 tables for preschoolers and illiterate people. Instead of letters and figures in these tables, images of geometric shapes and various lines are used.
Color blindness and the human profession
The limitations that the choice of a color blindness profession can be associated with are very important. First of all, these restrictions apply to professions where there is responsibility for life, one's own or other people. Daltonics are not accepted for military service, can not be pilots of aircraft, drivers of commercial vehicles and chemists. For these professions, annual medical examinations are required, which are an admission to professional activity. If a person is examined for color blindness, the rights in his profession are drastically reduced. He can engage in theoretical training of young professionals, perform office work related to their professional skills.
Color blindness and driver's license
If color blindness is a sentence in some professions, restrictions apply not to everyone for obtaining a driver's license. The expert's opinion is important here.
Driver's license and color blindness - the concepts are quite compatible, but only after the conclusion of an ophthalmologist. Only the doctor determines the type and degree of color blindness, therefore, and gives permission to the patient to manage a personal car. Color blinds can get the rights of categories "A" and "B", in which the presence of the mark "Without the right to work for hire" will be required.
To help colorblind
Scientists regularly offer new medical "gadgets" that can alleviate the fate of people with disabilities. It turns out that despite the fact that doctors can not fix the cone-sensors, it was possible to reprogram the brain for correct perception of color. Today, special glasses have appeared, in which narrow spectral bands 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 color-blinds see colors they did not even know existed: violet, bright green and bright red.