Misperception of colors 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 types, 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 perception
The human brain is able to distinguish a lot of various shades. The retina, more precisely, cone cells, is responsible for this ability. In a he althy 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 (in diseases affecting the area of the optic nerve or retina) orcongenital. 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 devices to perceive them, is called a trichromat. Pathological changes regarding color perception are divided into two main groups.
Birth defects tend to affect both 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 only perceive 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 D alton, 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 vehicles 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 mellitus.
- Intoxication of the body.
- Diseases of the nervous system.
The symptoms of color blindness do 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.
Diagnosis
To determine ifif 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, the Rabkin tests are widely known, which are passed by all drivers of vehicles.
All methods are the same in principle, presented in the form of drawings of 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 color perception, then he will not consider what is shown in the picture.
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 speci alties 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 examined in a complex.
The FALANT test is passed by all military servicemen 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 those who have slightly impaired perception can 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: main (27 tables) and control, which are used in case of questions and the need to detail the visual function.
Rules for testing on 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 test accuracy.
- There is a time limit of 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 the 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.
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 color perception disorders initially appear in one eye and then spread to the other. At the same time, visual acuity also decreases. It is important to identify the pathology at the initial stage.
Effective (surgical or therapeutic) methods of correction that would cure violations in the perception of colors are not yet available. But medicine does not stand still.
Color vision disorder and driver's license
For the first time about color blindness and driving a car, they started talking 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 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.
When it's time to change your license, the color test is inevitable. In 2018, the chances of gettingdriving licenses for colorblind 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 traffic lights, don't drive.
Conclusion
Persons with color vision disorders lead quite a normal life, except for 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 almost no chance of getting a driver's license.
Reviews
People suffering from color blindness write on the forums that this does not prevent them from living at all. They are used to seeing the world a little differently, but they do not find anything wrong with that. Lament overonly those who could not pass the Rabkin test and get a driver's license are the only ones with their problems.
Some people write that they can distinguish all colors perfectly (so they think), but during the test they could not name the numbers in all 27 pictures.
Reviews about color vision corrective glasses are mostly positive. Users note that with their help you can really see the world in a slightly different way. Branded glasses cost from 18,000 rubles, which is very expensive for some. But you can buy cheaper Chinese counterparts. They work too.
