Color-blindness test

Color blindness is one of the most common visual impairments. With this pathology, the eyes can not perceive one color or several at once.

As you know, color blindness is inherited, and they suffer from male faces. The causes of this vision impairment can also be various diseases, trauma, inflammation, eye and central nervous system tumors.

Definition and types of color blindness (color blindness)

Color blindness or color blindness is a violation of the perception of colors caused by a disorder of color vision.A person who does not have this pathology can recognize red, yellow and blue colors, which, when mixed, give different shades.

From the point of view of physiology, this can be explained as follows: in the yellow spot of the retina there are photoreceptor cells - cones. Their function is precisely the perception of colors. There are three kinds of cones, each of which has a special color pigment (red, blue, yellow).

If there are no pigments in the cones or it is very small, the color perception is violated.In most cases, there is a lack of red pigment, rarely there is a lack of blue.In the absence of a pigment, dichromasia is diagnosed, and three - achromatia. And with trichromasia in humans, the perception of one color is weakened.

In this case, three types of impaired perception are distinguished:

1. Type A- the perception of green or red color is almost completely absent.
2. Type B- a significant decrease in the perception of colors.
3. Type C- color perception is broken insignificantly.

Causes of color blindness:

• Hereditary predisposition(transmitted through the X-chromosome, so men are more likely to develop this pathology);
• Absence of pigment in cones or disruption of their work;
• Injuries, tumors and diseases of the eyes and central nervous system (optic nerve damage);
• Age-related changes in vision;
• Cataract (opacity of the lens prevents light from passing normally through the eyes);
• Diabetic macular degeneration;
• Acceptance of certain medicines;
• Parkinson's disease (the nerve impulse is broken to the photoreceptor cells and colors are detected);
• Stroke (similar to Parkinson's disease).

Color blindness can affect both one eye and two at once, but in this case it will be uneven.Sometimes color blindness can occur as a temporary phenomenon due to taking medications with a similar side effect.

Color blindness does not affect the visual acuity.

A person for a long time may not notice the symptoms of color blindness. The main signs of this visual impairment are:

1. Violation of perception of red color;
2. Violation of the perception of blue and yellow;
3. Disturbance of perception of green color;
4. Simultaneous impairment of perception of red, blue and yellow colors.
5. The sensitivity of the eyes to light (tears flow, pain in the eyes);
6. Blurring of contours of objects.

If color blindness was acquired during life, then it manifests itself in a gradual or abrupt violation of the perception of colors. In addition, he can progress.

There are three types of color blindness, depending on the violation of the production of pigment of a certain color:

1. Protanopia;
2. Deuteranopia;
3. Tritanopia.

Protanopia

The most common species are protanopia and deuteranopia.

Protanopia

Protanopia is the impossibility of perceiving red. This pathology is a partial form of blindness and is usually congenital.

In the case of protanopia in the photoreceptor cones there is no erythrolab pigment, which has the maximum sensitivity in the red-yellow part of the spectrum.A person with protanopia will perceive the yellow-green color as orange, and the blue color will coincide with the purple one.However, he will be able to distinguish between blue and green, and green from red.

Deeranopia

Deuteranopia is a violation of the perception of green color.

It occurs when there is no chloroblag pigment in the cones, which has a maximum sensitivity in the green-yellow spectrum.

In this case, the person will perceive the green color as blue, and the purple color does not distinguish it from the yellow-green color. However, a person can distinguish purple or red from green.

Tritanopia

Tritanopia is a violation of the perception of colors and shades in blue-yellow and red-violet spectra.In this case, there is no cyanolab pigment in the receptor cells, which has the maximum sensitivity in the blue-violet spectrum.

A person with tritanopia perceives yellow as blue, and purple does not distinguish from red. However, he can distinguish between purple and green.

Tritanopia may not have twilight vision.

The test for determining color blindness

To determine color blindness, anomaloscope instruments or special tests are used.Tests are conducted using special tables, for example, Stilling, Schaaf, Rabkin and so on.

The test for color blindness is carried out using the method of Rabkin. It is based on the use of the basic properties of colors.

Rubkin's test consists of diagnostic tables, which are filled with circles of different colors, but their brightness is the same.From these circles you can make different figures or figures. In a normal way, a person should not have difficulty in determining what is depicted on the table.But with daltonism it is impossible to understand what is depicted there. For young children, this test is not suitable, because it is impossible to understand what he sees. Therefore, indirect methods are used.If the child chooses from the proposed objects of different colors, only the soft gray, or if he draws, for example, the sky in red, then one should suspect the presence of problems.

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conclusions

Color blindness is a serious problem, and in some cases it makes life difficult. Unfortunately, at this time hereditary color blindness can not be cured.It can only be adjusted with special lenses or glasses, but they can not always give the desired effect.At least, at the ophthalmologist it is possible by means of tables for check for a color blindness to define a kind of the given infringement. Drivers should also take a color test on a regular basis. from this survey depends on their professional suitability.

Acquired color blindness is treated depending on the cause. If it is caused by eye trauma or disorders in the central nervous system, it can be cured by conservative or surgical methods. In the event that color blindness has appeared because of taking any medications, you should stop taking them.