Vision test for color perception for drivers. Violation of color vision: vision test for color perception, possible causes and how to correct color vision

There is also a parallel theory of opponent colors, according to which there are 3 pairs of opposite colors: white - black, green - red, blue - yellow. The brain receives information not about red, green and blue (as in the three-component theory), but about the difference in brightness of opposite colors, as a result, either white shades are perceived - or black, or green - or red, etc. There are no "greenish-red" or "blue-yellow" shades. However, this theory does not describe the direct mechanism of color perception.
At the end of the 20th century A non-linear theory of color vision also appeared. According to her, rods can perceive blue color, but they can only transmit a signal to the brain when interacting with cones. Therefore, at night, when the cones do not work, the rods cannot provide us with color vision, which is why “all cats are gray at night.” In cones, there are two light-sensitive areas: one is most sensitive to the yellow-green part of the spectrum, the other to the orange-red (chlorolab, erythrolab). This theory - the only one - explains the differences between cones that have not yet been found, but, despite this, it has not received wide acceptance.

Color vision disorders

Congenital disorders are not accompanied by a disorder of other visual functions, they are always observed in both eyes and are detected only with a special study. A person who correctly distinguishes all colors is called a normal trichromat, because. to get all the colors, we have to use the three primary colors.
A color anomaly is called a slight violation of color perception. They are inherited. Individuals with a color anomaly are also trichromats, but they are less able to distinguish some colors than normal-sighted trichromats and have been shown to use red and green in different proportions.
With deuteranomaly, there is a weakness in the perception of green, with protanomaly - red, with rare tritanomaly - blue. Dichromasia is characterized by a deeper impairment of color vision, in which the perception of one of the three flowers is completely absent: red (protanopia), green (deuteranopia) or blue (tritanopia). Monochromasia (achromasia, achromatopsia) means the absence of color vision or color blindness, in which only black and white perception is preserved.
All congenital disorders of color vision are commonly called color blindness, after the English scientist J. Dalton, who suffered from a violation of the perception of red and described this phenomenon.

Acquired disorders occur in diseases of the retina, optic nerve, or central nervous system. They can be observed in one or both eyes and are combined with other disorders of visual function. Most often, acquired disorders are manifested in the perception of the surrounding world in any color - yellow (xanthopsia), red (erythropsia) and blue (cyanopsia). Unlike congenital disorders that are permanent, acquired disorders resolve when their cause is removed.
The study of color perception is carried out by people whose profession requires normal color perception, for example, drivers. They use special color tables based on the recognition of one color against the background of another, or a device - an anomaloscope.

Color vision disorders are divided into congenital and acquired. Functional defects of the cone system may be due to hereditary factors and pathological processes at various levels of the visual system.

Congenital disorders of color vision are genetically determined and are recessively associated with sex. They occur in 8% of men and 0.4% of women. Although color vision disorders are observed much less frequently in women, they are carriers of the pathological gene and its transmitters.

The ability to correctly distinguish primary colors is called normal trichromacy, people with normal color perception - normal trichromats. Congenital pathology of color perception is expressed in a violation of the ability to distinguish light radiation, distinguishable by a person with normal color vision. There are three types of congenital color vision defects: a defect in the perception of red (protan defect), green (deuter defect) and blue (tritan defect).

If the perception of only one color is disturbed (more often there is a reduced discrimination of green, less often - red), the entire color perception as a whole changes, since there is no normal mixing of colors. According to the degree of severity, changes in color perception are divided into anomalous trichromasia, dichromasia and monochromasia. If the perception of any color is reduced, then this condition is called abnormal trichromasia.

Complete blindness to any color is called dichromacy(only two components differ), and blindness to all colors (black and white perception) - monochromatic.

Damage to all pigments at the same time is extremely rare. Almost all disorders are characterized by the absence or damage of one of the three photoreceptor pigments and thus are the cause of dichromasia. Dichromats have a peculiar color vision and often find out about their deficiency by accident (during special examinations or in some difficult life situations). Color vision disorders are called color blindness after the scientist Dalton, who first described dichromasia.

Acquired color vision disorder can manifest itself in a violation of the perception of all three colors. In clinical practice, the classification of acquired color vision disorders is recognized, in which they are divided into three types depending on the mechanisms of occurrence: absorption, alteration and reduction. Acquired disorders of color perception are caused by pathological processes in the retina (due to genetically determined and acquired diseases of the retina), the optic nerve, overlying parts of the visual analyzer in the central nervous system and can occur with somatic diseases of the body. The factors that cause them are varied: toxic effects, vascular disorders, inflammatory, demyelinating processes, etc.

Some of the earliest and most reversible drug toxic effects (after chloroquine or vitamin A deficiency) are monitored in repeated color vision tests; documenting the progress and regression of changes. When taking chloroquine, visible objects turn green, and with high bilirubinemia, which is accompanied by the appearance of bilirubin in the vitreous, objects turn yellow.

Acquired color vision disorders are always secondary, so they are determined randomly. Depending on the sensitivity of the research method, these changes can be diagnosed already with an initial decrease in visual acuity, as well as with early changes in the fundus. If at the beginning of the disease the sensitivity to red, green or blue color is disturbed, then with the development of the pathological process, sensitivity to all three primary colors decreases.

Unlike congenital, acquired color vision defects, at least at the onset of the disease, appear in one eye. Color vision disorders in them become more pronounced with time and may be associated with a violation of the transparency of optical media, but are more often related to the pathology of the macular area of ​​the retina. As they progress, they are joined by a decrease in visual acuity, visual field disturbances, etc.

To study color vision, polychromatic (multi-color) tables and occasionally spectral anomaloscopes are used. There are more than a dozen tests to diagnose color vision defects. In clinical practice, the most common are pseudoisochromatic tables, first proposed by Stilling in 1876. The tables of Felhagen, Rabkin, Fletcher, and others are currently used more often than others. They are used to identify both congenital and acquired disorders. In addition to them, Ishihara, Stilling or Hardy-Ritler tables are used. The most widespread and recognized in the diagnosis of acquired color vision disorders are panel tests created on the basis of the standard Munsell color atlas. Abroad, 15-, 85- and 100-shade Farnsworth tests of various colors are widely used.

The patient is shown a series of tables, the number of correct answers in different color zones is counted, and thus the type and severity of the deficiency (insufficiency) of color perception is determined.

Rabkin's polychromatic tables are widely used in domestic ophthalmology. They consist of multi-colored circles of the same brightness. Some of them, painted in one color, form, against the background of the rest, painted in a different color, some number or figure. These signs that stand out in color are easily distinguishable with normal color perception, but merge with the surrounding background with inferior color perception. In addition, there are hidden signs in the table that differ from the background not in color, but in the brightness of the circles that make them up. These hidden signs are distinguished only by persons with impaired color perception.

The study is carried out in daylight. The patient sits with his back to the light. Tables are recommended to be presented at arm's length (66-100 cm) with an exposure of 1-2 s, but not more than 10 s. If in order to detect congenital defects in color perception, especially during mass professional selections, in order to save time, it is permissible to test two eyes at the same time, then if acquired changes in color perception are suspected, testing should be carried out only monocularly. The first two tables are control, they are read by persons with normal and impaired color perception. If the patient does not read them, it is a simulation of color blindness.

If the patient does not distinguish between obvious signs, but confidently names hidden signs, he has a congenital color perception disorder. In the study of color perception, dissimulation is often encountered. To this end, the tables are memorized and recognized by their appearance. Therefore, at the slightest uncertainty of the patient, one should diversify the ways of presenting the tables or use other polychromatic tables that are inaccessible for memorization.

Anomaloscopes are devices based on the principle of achieving a subjectively perceived equality of colors by metered composition of color mixtures. The classic device of this type, designed to study congenital disorders of the perception of red-green colors, is the Nagel anomaloscope. By the ability to equalize a half-field of monochromatic yellow with a half-field composed of a mixture of red and green colors, the presence or absence of normal trichromacy is judged.

The anomaloscope allows diagnosing both extreme degrees of dichromasia (protanopia and deuteranopia), when the subject equates red or pure green to yellow, changing only the brightness of the yellow half-field, and moderately pronounced disorders in which the mixture of red and green is perceived as yellow (protanomaly and deuteranomaly ). According to the same principle as the Nagel anomaloscope, the anomaloscopes of Moreland, Naitz, Rabkin, Besancon and others were built.

Violations of color perception are a contraindication for work in some industries, a driver in all modes of transport, service in some types of troops. Normal color vision is necessary for the maintenance of conveyors, manual service trainers, etc.

T. Birich, L. Marchenko, A. Chekina

"Color vision disorders" article from the section

Men! Is it difficult for you to choose clothes so that they harmonize in color, choose ripe fruits among fruits, distinguish color images on a computer monitor, green and red traffic lights? Or does someone help you do it? This suggests that you have a color vision disorder or, as they also call it, a violation of color vision.

This problem is observed most often in every 12th Caucasian man and in every 200th woman. Most color blind people see other colors in addition to black and white, but they perceive some of them differently than a person with normal vision. As a rule, color vision impairment is inherited. The damaged gene disrupts the light sensitivity of retinal cells or the inner lining of the eye. But sometimes color vision can be impaired by a disease, then you need to contact an ophthalmologist.

In the human retina, there are usually three types of light-sensitive cells or cones that are sensitive to light waves of a certain wavelength and correspond to colors: blue, green and red. Each type of cone absorbs its own light wave and sends impulses to the brain and the person perceives the color correctly. But when color vision is impaired, the sensitivity of the cones decreases to one color or several, or the perception of the wavelength changes and affects color perception. Most people with this disorder are color blind: green, yellow, orange, red, and brown. Therefore, they do not notice green mold on black bread or yellow cheese and do not distinguish a blond from a red-haired person. When the sensitivity of cones, which are responsible for the perception of red, is sharply reduced, then a red rose seems black to them. Cases of color blindness to blue are very rare.

As already mentioned, photosensitivity disorder is inherited and, as a rule, is congenital. But many learn about it only when they grow up. The fact is that in children, the impaired perception of colors is often compensated by the ability to distinguish them unconsciously by brightness or contrast. Children associate their perceptions with common color names. In addition, they learn to distinguish objects by shape or texture, and not by color. And as adults, they learn that they suffer from a violation of color vision since childhood.

The school often uses colored aids, especially in elementary grades. And if the child does not know how to correctly distinguish colors, then teachers and parents mistakenly conclude that the child is not capable of learning. And in fact, he may have a violation of color perception. Sometimes the teacher even punishes the child for drawing green people, brown leaves on trees and pink clouds, but the child considers such colors to be completely normal, he just has color vision impaired. In some countries, for this reason, even young children are examined for color blindness.

Although color perception disorder is considered incurable, it does not worsen other visual functions over the years. But, nevertheless, this disease in some causes emotional distress.

Why is color vision impaired mostly in men? The X chromosome is responsible for inherited color perception. Women have two X chromosomes, while men have one X chromosome and the other Y . When a gene is damaged on one X chromosome in a woman, it compensates for a healthy gene on the other X chromosome and she retains normal vision. And men do not have a spare X chromosome, so the defect is not compensated.

How is a color vision test performed?

An eye test for color perception is carried out according to special tables with the image of many multi-colored circles. The 38 Ishihara tables are often used for this purpose. If a person has normal vision, then looking at the tests on the left in daylight, he will see the numbers 42 and 74. If a person has a violation of the perception of red and green (this most often happens), then he does not distinguish the number above, but sees the number 21 below. The tests given here are only an example, as the examination should be carried out by a qualified doctor. If a violation is detected, the doctor will prescribe an additional examination to determine the cause - it is hereditary or acquired.

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Incorrect color perception is a pathological change in visual function and can significantly affect the quality of life. These disorders are observed both congenital and acquired. Consider the features of color vision disorders, their varieties, causes, methods of diagnosis and correction, as well as how this may affect the receipt or replacement of a driver's license.

What is color vision

The human brain is capable of distinguishing a wide variety of shades. The retina, more precisely, cone cells, is responsible for this ability. In a healthy person, color is perceived by three devices that are sensitive to waves of different wavelengths and radiation. If the eye does not distinguish one color from another, this indicates a violation of color perception.

Pathology can be acquired (with diseases affecting the area of ​​the optic nerve or retina) or congenital. In this case, the violations are called color blindness. With such a diagnosis, a driver's license is not issued.

Types of color vision disorders

A person who perceives all three primary colors (red, green and blue), that is, uses three apparatus to perceive them, is called a trichromat. Pathological changes related to color perception are divided into two main groups.

Congenital disorders, as a rule, apply to two eyes at once. They can be identified only with the help of a special study. Color blindness does not entail a loss or reduction in the quality of other visual functions. Most often, congenital anomalies are inherited. These faces perceive only two colors, but in a slightly different proportion than trichromats.

Types of congenital pathology:

• Deuteranomaly - it is the green tint that is poorly perceived.
• Protanomaly - the red color is almost invisible.
• Tritanomaly - invisible blue tint.
• Dichromasia - visual receptors do not perceive one of the three shades at all.
• Monochromasia - “color blindness”, that is, a person sees everything only in black and white.

Colorblindness pathology is named after the scientist John Dalton, who himself suffered from impaired perception since childhood.

Acquired color vision disorders are most often the result of diseases of the retina, central nervous system or optic nerve. Pathology can spread to one or both eyes at once.

Types of acquired disorders:

• Xanthopsia - everything is perceived in yellow.
• Erotropsia - in red.
• Cyanopsia - in blue.

Unlike congenital pathology, which cannot be corrected, acquired anomalies can be eliminated if the cause of the disease is eliminated.

Color perception is checked with an instrument called an anomaloscope. Railway drivers and workers transport must pass this study.

Causes and symptoms

As noted above, the congenital type of color perception disorder is hereditary. The disease is transmitted from the mother via the X chromosome. Most often, representatives of the stronger sex suffer from color blindness, since they lack the maternal chromosome with such a gene. In order for a girl to be born with congenital color blindness, it is also necessary that her maternal grandmother also suffer from impaired visual function regarding the perception of shades.

Acquired pathology can occur for the following reasons:

• Stroke.
• Head injury.
• Cataract or other pathology of visual function in the absence of therapy.
• Diabetes.
• body intoxication.
• Diseases of the nervous system.

The symptomatology of color blindness does not depend on the type of disorder (congenital or acquired). It lies in the fact that a person cannot distinguish certain shades, while visual acuity may not be impaired.

Diagnostics

To determine if a person has a violation of color perception, ophthalmologists conduct a series of studies. The most commonly used polychromatic tables are Fletcher-Gambling, Ishihara, Stilling and others. In the Russian Federation, Rabkin's tests are widely known, which are passed by all drivers of vehicles.

All methods are the same according to the principle of action, they are presented in the form of drawings from dots or circles of different diameters and shades. If you look closely at the picture, then a certain picture made in other colors will be visible through the main background. If a person has a pathology regarding the perception of color, then he will not consider what is shown in the figure.

Also in ophthalmology, the FALANT test and a device called an anomaloscope are used. It is used to test people when they are admitted to certain specialties where it is important to clearly distinguish colors. With the help of the device, it is possible to diagnose a type of violation, as well as how brightness, age, noise, training, medications affect a person’s color perception, that is, visual receptors are studied in a complex.

The FALANT test is passed by all persons liable for military service in America. To do this, you need to determine the color that shows the beacon at a certain distance. Those who suffer from color blindness do not pass such a test. But 30% of people who have slightly impaired perception can successfully pass the test.

Rabkin's tables

Violations of color perception are allowed when obtaining a driver's license, but only to a small extent. The most common in Russia are Rabkin's tests, which consist of 48 tables. They are divided into two groups: basic (27 tables) and control, which are used in case of questions and the need to detail the visual function.

Rules for testing according to Rabkin's tests:

• The monitor screen on which each picture is displayed should not be too bright or dim.
• All tables should be at eye level. Positioning higher or lower may affect the accuracy of the test.
• There is a time limit - 5 seconds per picture.

As a rule, to check whether a person has color blindness, it is enough to pass the test on the first 27 pictures. The specialist indicates the diagnosis, as well as the degree of anomaly (weak, moderate or strong).

Methods for correcting violations

Congenital pathology is not yet correctable, although Western scientists have invented special contact lenses with which color-blind people can see the world in different colors. Geneticists are also developing methods to introduce into the cells of the retina of the eye genes that are responsible for the perception of shades.

Congenital inability to distinguish colors does not progress. Colorblind people have been learning colors since childhood, and this one does not affect their quality of life in any way.

To cure acquired color blindness, it is worth identifying the root cause of the pathology and eliminating it. If the anomaly appears as a result of age-related changes, it is practically incurable, although people have a chance to correct the situation by replacing the lens. If color perception is caused by the influence of some chemical preparation, it must be canceled. If the pathology was the result of an injury, it all depends on the degree of destruction of the retina.

Acquired disorders of color perception initially appear in one eye, and then spread to the other. At the same time, visual acuity also decreases. It is important to identify pathology at an early stage.

There are no effective (surgical or therapeutic) methods of correction that would cure violations in the perception of colors. But medicine does not stand still.

For the first time, they started talking about color blindness and driving a car at the end of the 19th century. In 1975, there was a major railway accident in Sweden. The driver turned out to be the culprit, who could not recognize the red color of the traffic light. After this incident, drivers and railway workers began to be additionally checked not only for the quality of vision.

Many car owners are interested in the question of whether it is necessary to replace a driver's license in case of a violation of color perception?

In Russia, until 2012, people with a mild degree of color blindness were allowed to drive a car (categories B and C), using it for personal purposes. In 2017, the rules have changed. According to the legislation of the Russian Federation, it is no longer possible for color-blind people to drive a car. Such a driver poses a serious danger to other road users and pedestrians.

If it's time to change your driving license, a color test is inevitable. In 2018, the chances of getting a driver's license from color blind people are minimal. In developed countries, it is allowed to drive a vehicle for those who constantly wear colored contact lenses or glasses. With the help of them, the color-blind world becomes multi-colored, that is, the way an ordinary person sees it.

Is it possible not to pass the test according to Rabkin's tables

Great yogis or mahatmas said about the violation of color perception that these are special people. Unfortunately, such car owners cannot successfully pass the test for the ability to distinguish colors. Theoretically, you can memorize all the pictures. But the doctor may show them out of order, which significantly reduces the chances of success.

Some believe that you can always negotiate with an ophthalmologist. But in this case, it is worth assessing whether such a risk is really justified. After all, not only other road users, but also the driver himself can be at risk. If you can't tell how the colors change at the traffic lights, you shouldn't drive.

Conclusion

Persons with color perception disorders lead a completely normal life, with the exception of some discomfort. Color-blind people are somewhat limited in their choice of profession; they cannot become military men. Also, since 2017, car owners who suffer from color blindness have practically no chance of obtaining a driver's license.

Color vision is a unique natural gift. Few creatures on Earth are able to distinguish not only the contours of objects, but also many other visual characteristics: color and its shades, brightness and contrast. However, despite the apparent simplicity of the process and its routine, the true mechanism of color perception in humans is extremely complex and not known for certain.

There are several types of photoreceptors on the retina: sticks and cones. The sensitivity spectrum of the former allows for object vision in low light conditions, and the latter for color vision.

At present, the three-component theory of Lomonosov-Jung-Helmholtz, supplemented by the opposing concept of Hering, has been adopted as the basis for color vision. According to the first, on the human retina There are three types of photoreceptors(cones): "red", "green" and "blue". They are mosaically located in the central region of the fundus.

Each of the species contains a pigment (visual purple), which differs from the others in its chemical composition and ability to absorb light waves of different wavelengths. The colors of the cones, by which they are called, are arbitrary and reflect the light sensitivity maxima (red - 580 microns, green - 535 microns, blue - 440 microns), and not their true color.

As can be seen from the graph, the sensitivity spectra overlap. Thus, one light wave can to some extent excite several types of photoreceptors. Getting on them, the light generates chemical reactions in the cones, leading to the “burning out” of the pigment, which is restored after a short period of time. This explains the blindness when we look at something bright, such as a light bulb or the sun. The reactions that arose as a result of hitting a light wave lead to the formation of a nerve impulse that travels along a complex neural network to the visual centers of the brain.

It is believed that it is at the stage of signal passage that the mechanisms described in Goering's opposite concept are activated. It is likely that nerve fibers from each photoreceptor form so-called opponent channels ("red-green", "blue-yellow" and "black-white"). This explains the ability to perceive not only the brightness of colors, but also their contrast. As evidence, Hering used the fact that it was impossible to imagine such colors as red-green or yellow-blue, and also that when these, in his opinion, "primary colors" were mixed, they disappeared, giving white.

Taking into account the above, it is easy to imagine what will happen if the function of one or more color receivers decreases or is completely absent: the perception of the color gamut will change significantly compared to the norm, and the degree of change in each case will depend on the degree of dysfunction, individual for each color anomaly.

Symptoms and classification

The state of the color-perceiving system of the body, in which all colors and shades are fully perceived, is called normal trichromasia(from Greek chroma - color). In this case, all three elements of the cone system ("red", "green" and "blue") work in full mode.

At anomalous trichromats violation of color perception is expressed in the indistinguishability of any shades of a particular color. The severity of changes directly depends on the severity of the pathology. People with mild color anomalies are often not even aware of their peculiarity and learn about it only after passing medical examinations, which, according to the results of examinations, can significantly limit their career guidance and further work.

Anomalous trichromasia is subdivided into protanomaly- impaired perception of red color, deuteranomaly- violation of the perception of green and tritanomaly- violation of the perception of blue color (classification according to Chris-Nagel-Rabkin).

Protanomaly and deuteranomaly can be of different severity: A, B and C (in descending order).

At dichromasia a person lacks one type of cone, and he perceives only two primary colors. An anomaly due to which red is not perceived is called protanopia, green is deuteranopia, blue is tritanopia.

However, despite the apparent simplicity, to understand How do people with altered color vision actually see?, is extremely difficult. The presence of one non-functioning receiver (for example, red) does not mean that a person sees all colors except this one. This gamut is individual in each case, although it has a certain similarity with that of other people with a color vision defect. In some cases, there may be a combined decrease in the functioning of cones of various types, which introduces "disturbance" into the manifestation of the perceived spectrum. Cases of monocular protanomalies can be found in the literature.

Table 1: Perception of colors by individuals with normal trichromasia, protanopia and deuteranopia.

The table below reflects the main differences in the perception of colors by normal trichromats and individuals with dichromasia. Protanomalies and deuteranomals have similar impairments in the perception of certain colors depending on the severity of the condition. The table shows that the definition of protanopia as blindness to red, and deuteranopia - to green is not entirely correct. Research scientists have found that protanopes and deuteranopes do not distinguish between red or green colors. Instead, they see shades of greyish-yellow of varying lightness.

The most severe degree of color vision impairment is monochromacy- complete color blindness. Allocate rod monochromasia (achromatopsia), when cones are completely absent on the retina, and with a complete disruption of the functioning of two of the three types of cones - cone monochromasia.

In case of rod monochromacy When there are no cones on the retina, all colors are perceived as shades of gray. Such patients also usually have low vision, photophobia, and nystagmus. At cone monochromacy different colors are perceived as one color tone, but vision is usually relatively good.

To designate color perception defects in the Russian Federation, two classifications are simultaneously used, which confuses some ophthalmologists.

Classification of congenital disorders of color perception according to Chris-Nagel-Rabkin

Classification of congenital disorders of color perception according to Nyberg-Rautian-Yustova

Main difference between them lies only in the verification of partial violations of color vision. According to the Nyberg-Rautian-Yustova classification, the weakening of cone function is called color weakness, and depending on the type of photoreceptors involved, it can be divided into proto-, deuto-, tritodeficiency, and according to the degree of impairment - I, II and III degree (ascending). There are no differences in the upper part of the schematically reflected classifications.

According to the authors of the latter classification, a change in the color sensitivity curves is possible both along the abscissa (change in the range of spectral sensitivity) and along the ordinate (change in the sensitivity of cones). In the first case, this indicates an anomalous color perception (anomalous trichromasia), and in the second, a change in color strength (color weakness). Persons with color weakness have reduced color sensitivity of one of the three colors, and brighter shades of this color are needed for proper discrimination. The required brightness depends on the degree of color weakness. Anomalous trichromasia and color weakness, according to the authors, exist independently of each other, although they often occur together.

Also, color anomalies can be sort by color spectrum, the perception of which is impaired: red-green (protano- and deuteron disorders) and blue-yellow (triton disorders). Origin all violations of color perception can be congenital and acquired.

color blindness

The term "color blindness", which has become widely used in our lives, is more slang, since in different countries it can mean different color vision disorders. We owe its appearance to the English chemist John Dalton, who first described this condition in 1798, based on his feelings. He noticed that the flower, which in the daytime, in the light of the sun, was sky blue (more precisely, the color that he considered sky blue), in the light of a candle looked dark red. He turned to those around him, but no one saw such a strange transformation, with the exception of his own brother. Thus, Dalton guessed that something was wrong with his vision and that the problem was inherited. In 1995, studies were carried out on the preserved eye of John Dalton, during which it turned out that he suffered from deuteranomaly. It usually combines "red-green" color perception disorders. Thus, despite the fact that the term color blindness is widely used in everyday life, it is incorrect to use it for any violation of color vision.

This article does not deal in detail with other manifestations of the organ of vision. We only note that most often patients with congenital forms of color perception disorders do not have any special, specific disorders for them. Their vision is no different from that of an ordinary person. However, patients with acquired forms of pathology may experience various problems, depending on the cause that caused the condition (decrease in correctable visual acuity, visual field defects, etc.).

Causes

Most often in practice congenital disorders occur color perception. The most common of these are "red-green" defects: protano- and deuteranomaly, less often protano- and deuteranopia. Mutations in the X chromosome (linked to sex) are considered to be the cause of the development of these conditions, as a result of which the defect is much more common in males (about 8% of all men) than females (only 0.6%). The occurrence of different types of "red-green" color vision defects is also different, which is shown in the table. About 75% of all violations of color perception are deuteron violations.

In practice, congenital tritan defect is extremely rare: tritanopia - in less than 1%, tritanomaly - in 0.0001%. The frequency of occurrence in both sexes is the same. In such people, a mutation is determined in a gene located on the 7th chromosome.

In fact, the frequency of occurrence of color perception disorders among the population can vary significantly depending on ethnicity, territorial affiliation. So, on the Pacific island of Pingelap, which is part of Micronesia, the prevalence of achromatopsia among the local population is 10%, and 30% are its hidden carriers in the genotype. The occurrence of a “red-green” color defect among one ethno-confessional group of Arabs (Druze) is 10%, while among the indigenous inhabitants of the island of Fiji it is only 0.8%.

Some conditions (inherited or congenital) can also cause color vision problems. Clinical manifestations can be detected both immediately after birth and throughout life. These include: cone and rod-cone dystrophy, achromatopsia, blue cone monochromasia, Leber's congenital amaurosis, retinitis pigmentosa. In these cases, there is often a progressive deterioration in color vision as the disease progresses.

Diabetes, glaucoma, macular degeneration, Alzheimer's disease, Parkinson's disease, multiple sclerosis, leukemia, sickle cell anemia, brain injury, damage to the retina by ultraviolet light, vitamin A deficiency, various toxic agents (alcohol, nicotine) can lead to the development of acquired forms of color vision impairment. medicines (plaquenil, ethambutol, chloroquine, isoniazid).

Diagnostics

At present, color vision assessment is given undeservedly little attention. Most often, in our country, verification is limited to demonstrating the most common tables of Rabkin or Yustova and an expert assessment of suitability for a particular activity.

Indeed, a violation of color perception often has no specificity for any disease. However, it can indicate the presence of those at a stage when there are no other signs. At the same time, the ease of use of tests makes it easy to apply them in everyday practice.

The simplest can be considered color comparative tests. For their implementation, only uniform lighting is necessary. The most accessible: alternate demonstration of the source of red color to the right and left eyes. At the beginning of the inflammatory process in the optic nerve, the subject will note a decrease in the saturation of tone and brightness on the affected side. Also, the Kolling table can be used to diagnose pre- and retrochiasmal lesions. In pathology, patients will note discoloration of the images on one side or another, depending on the localization of the focus.

Other methods that help in diagnosing a color vision disorder are pseudo-isochromatic tables and color ranking tests. The essence of their construction is similar, and is based on the concept of a color triangle.

The color triangle on the plane reflects the colors that the human eye can distinguish.

The most saturated (spectral) are located on the periphery, while the degree of saturation decreases towards the center, approaching white. The white color in the center of the triangle is the result of a balanced excitation of all types of cones.

Depending on which type of cone is underfunctioning, a person cannot distinguish certain colors. They are located on the so-called lines of non-distinction, converging to the corresponding corner of the triangle.

To create pseudo-isochromatic tables, the colors of the optotypes and the background (“masking”) surrounding them were obtained from different segments of the same line of indistinguishability. Depending on the type of color anomaly, the subject is not able to distinguish between certain optotypes on the displayed cards. This allows you to identify not only the type, but also in some cases the severity of the existing violation.

Developed many options for such tables: Rabkina, Yustova, Velhagen-Broschmann-Kuchenbecker, Ishihara. Due to the fact that their parameters are static, these tests are better suited for diagnosing congenital anomalies of color perception than acquired ones, since the latter are characterized by variability.

Color ranking tests are a set of chips whose colors correspond to the colors in the color triangle around the white center. A normal trichromat is able to arrange them in the required order, while a patient with impaired color perception is only in accordance with the lines of indistinguishability.

Currently used: Farnsworth 15-chip panel test (saturated colors) and its modification Lanthony with desaturated colors, Roth 28-shade test, as well as Farnsworth-Munsell 100-shade test for more detailed diagnostics. These methods are more suitable for identifying acquired color perception disorders, as they help to assess them more accurately, especially in dynamics.

A certain disadvantage in the use of pseudo-isochromatic tables and color ranking tests is the strict requirements for illumination, the quality of the displayed samples, storage conditions (it is necessary to avoid burnout, etc.).

Another method that helps in the quantitative diagnosis of color perception disorders is the anomaloscope. The principle of its operation is based on the formulation of the Rayleigh equation (for the red-green spectrum) and Moreland (for blue): the selection of color pairs, which gives a color indistinguishable from a monochromatic (from one wavelength color) sample. Mixing green (549 nm) and red (666 nm) gives the equivalent yellow (589 nm), with the differences balanced by the change in brightness of the yellow (Rayleigh's equation).

A Pitt chart is used to record the results. The colors obtained by mixing red and green are placed along the abscissa depending on the amount of each of them in the mixture (0 - pure green, 73 - pure red), and the brightness - along the ordinate. Normally, the resulting color is equal to the control is 40/15, respectively.

In case of violations of the "green" color receiver, to obtain such equality, more green is needed, and in case of a "red" defect, add red and lower the brightness of yellow. In cerebral achromatopsia virtually any ratio of red and green can be equated with yellow.

The disadvantage of the technique may be the need for special expensive equipment.

Treatment

Currently, there is no effective treatment for color vision disorders. However, spectacle lens manufacturers are constantly trying to develop special filters that will change the spectral sensitivity of the eye. In fact, full-fledged scientific research in this direction has not been conducted, so it is not possible to reliably judge their effectiveness. Judging by the complexity and versatility of the color discrimination process, their usefulness seems doubtful. Acquired color vision disorders are able to regress when the cause that caused them is eliminated, but also do not have a specific treatment.

Due to the impossibility of treating these conditions, the main issue remains the expediency and degree of restriction of persons with color anomalies, especially those with congenital changes in color perception. In different countries of the world, this issue is approached in different ways. Sometimes people with similar color vision problems may have radically different opportunities for choosing a profession, participating in traffic, etc. In my opinion, given the wide prevalence of anomalies, it makes sense not to follow the path of limiting such people in their activities, but to try to level the influence of the color factor on their work and life.