A person's ability to see different colors and shades is due to the proper functioning of the organs of vision. This process in medicine is called color perception. Due to the fact that modern society spends most of its time in front of gadget screens, various visual impairments are increasingly being recorded. This includes misperception of the color spectrum.
How to identify such a pathology? For this, medical instrumental methods or specially designed color perception tests are used. What are such diagnostic techniques and whether it is possible to check vision at home, we will tell in our material.
What is color vision?
First, it should be explained what color perception is. This is the ability of the human organs of vision to perceive light reflection and convert it into a complete image. What shade a person sees in front of him is influenced by various external physical factors: lighting, angle of refraction, distance, and even the psycho-emotional state of the individual at a particular moment.
There are different theories about the mechanism of color perception. Commonis the so-called three-component. Its essence lies in the fact that the ability to color perception is activated under the influence of green, red and blue. If a person distinguishes such colors and their shades, then such a color perception is called trichromasia in medicine. Tests for color perception are developed precisely on the theoretical foundations of this theory.
Color perception disorders
Unfortunately, in the age of electronic gadgets, few can boast of excellent vision. Violation of color perception is one of the most common pathologies. Such deviations in medicine are called color blindness. Color blindness can be complete - then a person sees everything around in gray, or partial. Most often, violations occur in the green and red parts of the spectrum. Such vision problems are not only acquired, but also congenital.
It is especially important to pass a color perception test for drivers, as people usually do not even realize that they see colors distorted or do not distinguish them at all. And this condition is extremely dangerous for people driving a vehicle and pedestrians.
Diagnostic Methods
How is human color perception diagnosed? In modern medicine, there are two methods for detecting such pathologies of vision:
- instrumental using an anomaloscope (there are various models: Nagel, Rabkin, GOI device);
- color perception tests.
First methodinvolves an examination in a special medical center, which is equipped with the specified equipment. But the tests can even be passed independently at home.
Tests for diagnosing color blindness
In modern ophthalmology, color perception is checked using special tables (Ishihara or Rabkin). They represent a certain system of multi-colored dots. It will not be difficult for a person with normal visual perception to determine what is depicted on such cards. But patients with impaired color perception will not be able to select a “hidden” figure or number from the dots.
The most popular are Rabkin's cards. They are divided into 2 groups:
- For diagnosing the type of color perception disorder (these are tables from 1 to 27).
- To confirm the preliminary diagnosis (tables 28 to 48).
How is the test done?
With the help of this test, it is easy to check your eyesight even at home. The color perception of a person at the first stage is diagnosed using tables 1 to 27. In order for the results to be true, the following diagnostic recommendations should be followed:
- Test should be done in natural daylight. In this case, the patient should sit with his back to the light source, and the examiner - opposite him at a distance of 1 meter.
- It is important to diagnose when the patient feels normal. Symptoms such as headache, weakness, fatigue, depression and stressconditions can lead to false results.
- Tables of color perception should be shown to the subject vertically at eye level.
- The patient is given up to 7 seconds to think about the answer.
The answers of the subject are recorded in a special form for the convenience of their further interpretation and diagnosis of color perception disorders.
Rabkin's tables
What is Rabkin's table? This is an image of numbers and geometric shapes, consisting of dots of different colors. But the saturation of the palette is the same. Thus, a person with normal color perception can easily see the "encrypted" image. Whereas in the presence of pathologies, it will be difficult for the patient to select colors and build a complete picture.
Note that the first two tables are so-called snags. First of all, they are training. And secondly, they determine the simulation of the disease, since even a person with impaired color perception can decipher the figures depicted on them.
Table transcript
In order to decipher the result, it is required to know the correct answer of each table, as well as the diagnostic purpose of each card. So, the answers to the Rabkin test are as follows:
- The first chart shows the number 96. This card is for explaining the test.
- On the next one you can see the figures - a square and a triangle. The goal is to reveal the simulation.
- On the card underthis number is the number 9. If the patient is color blind, he will see the five.
- On the fourth table, a normal person sees a triangle, and in the presence of visual impairment - a circle.
- Rabkin's table number 5 contains the number 13. In case of color blindness, the subject will see 6.
- There are 2 geometric shapes here - a circle and a triangle. But a person with impaired color perception will not be able to distinguish between shapes.
- This card is also a fake. The number 9 depicted on it will be seen by both he althy people and those with color perception disorders.
- The painted five will be seen only by he althy people.
- If there is a pathology in the perception of the red color spectrum, then the subject will find the number 8 or 6 on this table. Whereas the nine is actually depicted.
- A person who sees the numbers 68, 66 or 69 has deviations in color perception. In the absence of anomalies, the subject will find the number 136.
- This card will be solved by both he althy people and those with vision pathology. Here is the number 14.
- Won't be able to detect the number 12 on this card for patients who can't see the red spectrum well.
- A circle and a triangle are drawn on this table. People who have an anomaly in the perception of the green spectrum will only be able to see the triangle. If the orientation in the red part of the spectrum is disturbed, then patients will only detect a circle.
- The numbers 3, 6 and 0 are encrypted here. With an anomaly in the green spectrum, people see one and six. And if the color perception of red is impaired, then patients will marknumbers 1, 0 and 6.
- Only he althy people will be able to see the encrypted geometric shapes (triangle, circle and square). In the presence of pathologies, patients will offer a variety of answers.
- On this card a he althy person will see the number 96. If the perception of the red spectrum is disturbed, then only nine will be noticeable. In case of problems with orientation in the green area, the patient will only point to the six.
- This table shows such geometric shapes as a triangle and a circle. In the presence of anomalies, a person will be able to detect only one of these drawings.
- This table is different from the previous ones. Here a he althy person will see horizontal and vertical rows of multi-colored squares. Whereas in violation of color perception, the subjects note the uniformity of individual rows or columns.
- The number 25 is encrypted on this card. If there is an anomaly of vision, a person will only see a five.
- If the subject distinguishes geometric shapes on this table (circle and triangle), then everything is in order with his color perception. A colorblind person will not be able to distinguish the pictures at all.
The remaining 7 tables are identical to those already described.
Interpretation of results
So, the color perception test was carried out. How to decipher the results? Any number of incorrect answers gives reason to suspect a violation of color perception. In this case, the second stage of testing is carried out using tables 28-48 to clarify the form of the pathology. But the final diagnosis can only be made by an ophthalmologist.
Color perception tests are a quick and affordable way to diagnose visual impairment. But it is important to remember that if all recommendations are not followed, the results may be false. Therefore, you should not engage in introspection, and even more so treatment, without consulting a specialist.
