How is the test of color vision

Verification of vision for color perception is compulsorily carried out when employing in some specialties. It allows you to identify various problems in a timely manner and take action. Tests for color blindness are carried out by hospitals, clinics, medical centers, if desired, a mini-test can be completed independently - using a special table (either conventional or online). During the diagnosis in the medical institution, the doctor shows the patient a special scheme containing letters, symbols, pictures and / or checks using a computer device. More details about the types of color blindness and the features of the test are given below.

Definition of color blindness

Color blindness or color blindness is an innate, less commonly acquired, disease, based on the lack of perception of certain colors and shades.

This pathology carries a color-sensitive defect, in which the nerve cells of the retina, called cones and rods, do not have the necessary elements for processing the color efficiency of the image.

Each cone and wand have 3 sets of elements: chlorolab, responsible for the perception of the yellow-green spectrum, erythrolab - yellow-red spectrum, cyanolab - the perception of blue-violet rays.People who have all three pigments are called trichormats, while, depending on the absence of a certain pigment, color-blinds have their scientific-ophthalmological names. Next, each type of color blindness will be considered.

You can classify color blindness to partial and complete. Partial refers protomanomaly, tritanomaliyu, deuteranomaliyu. To full - this is protanopia, tritanopia, deuteranopia and achromatopsia.

To pass the test for color blindness it is possible in this article.

Color blindness can develop in relation to red or green and, accordingly, there are different types.

Protanomalia, protanopia

- non-perception of red colors and shades.Absence or partial presence of erythrolab.

Disturbances in perception of the red pigment are diagnosed most often. About 8% of all men have a red-green defect, in women, this pathology is diagnosed in 0.5% of all cases. About 3/4 of the patients in this group are abnormal trichromates.

Among the trichromant men is more - pathology is diagnosed in them only in 8% of cases, while for women this indicator is 0.5%.

Tritanopia, Tritanomalia

-non-perception of blue colors and shades.Absence or partial presence of cyanol.

Protanopia - the name of an abnormal deviation from normal color perception, which occurs, like trichromantopia, in 8% of men and 0.5% of women(the data are approximate). Such color blindness is partial and usually has an innate character. The patient does not distinguish between shades of blue and blue.

With protanopia, the patient does not distinguish between yellow-green and blue color shades.

Protanopia develops in those cases, if there are no photosensitive pigment of erythrolab in the retinal cones. As a result, the green color is perceived as orange, while the blue color is from green, and the green from the dark red patient is normal.

Deuteranopia, deuteranomalia

-non-perception of green colors and shades.Absence or partial presence of chronolab.

Deuteranopia is a form of partial blindness that occurs in only 1% of people.Pathology in most cases is congenital, characterized by reduced sensitivity to colors and their shades mainly of the green spectrum.

Deuteranopia occurs in only 1% of all patients with color blindness.

Deuteranopes lack the M-cone pigment, resulting in a low sensitivity to waves of the green part of the spectrum of medium length. At the same time, they perceive the short-wavelength part of the color spectrum as blue, and long-wavelength part as yellow. Light green color deuteranopy see dark red, purple blue, and purple gray. Pathology is not curable.

Achromatopsia

- non-perception of all shades and colors.Absence of all pigments responsible for color image processing.

This pathology is diagnosed least often, characterized by complete color blindness, when a person perceives only black and white colors.

Causes

As mentioned earlier, color blindness is in most cases a congenital disease transmitted in the X chromosome by a recessive type.Transmission occurs from mother to son, which reduces the statistics to the prevalence of the disease among men. Judging by such data, the distribution of color blindness among men is 6-8% per 1000 units of the population, when among women the disease occurs in a maximum of 4 people for the same number of people.

Separately it is necessary to say that color blindness is not always diagnosed as a disease.In some cases, anomalies in the development of perception are so insignificant that in adults and children a compensatory reaction develops.For example, with a weak perception of red color, a person will clearly see green and blue tones and shades. A vivid example of this is the color of khaki. For people with disabilities, it will be rich and clear, while for an ordinary person, this color is rolling and merging.

Statistics of disease occurrence

Allocate also the acquired color blindness.As a rule, in the case of acquired disease, only one eye is damaged. Color blindness is referred to as a progressing disease, up to achromatopsia. Predecessors can become lesions of the optic nerve (neuritis, stagnant discs, atrophy), lesions of the retina and inflammation of the cornea.

As a rule, if such complication has begun, then a person, even after curing or arresting the underlying disease, is not able to restore color perception.

Tests for the definition of color blindness

The color perception test involves showing images to the test, which consist of circles of different colors and form figures or certain figures.In those cases when there are problems with color perception, the person does not see the figure at all, sees, but not all, or perceives the signs in a distorted way (not in the form in which they are actually represented). The test person should feel normal, and the test itself is carried out strictly in a well-lit room, the tables are located at a comfortable distance from the eyes.Recognition time - up to 10 seconds.

Diagnostic features:

• Figures 6 and 9 distinguish absolutely all people.This plate is a control.
• People with unbroken perception of color(trichromates) see the figure 12 in the picture, protanopes and deytrans - 6.
• Patients with normal vision, as well as impaired perception of red, distinguish only two digits - 9 and 6, green - 6.
• If the color perception is not disturbed, a person sees a triangle and a circle,if the perception of a green triangle is violated, a circle is red.

You can independently test at home, if you so desire, but for medical conclusion go to the clinic.

Consider the moment that the simplest color perception test gives approximate results. The exact diagnosis can be made only by the doctor in the course of deeper diagnosis (he uses computer devices and enlarged tablets).

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conclusions

Color blindness can develop in relation to red or green, so there are different types. Most often, color blindness is diagnosed in men. To determine perceptual disturbances, a special test is performed - independently on the tables or in the clinic.

Also read about how to determine visual acuity and what is pachymetry.