Anomalies of color vision are a violation of color perception by the visual analyzer.
Color vision is provided by cones. There are three types of cones: those that absorb the blue-violet part of the spectrum, green, and the yellow-red part of the spectrum. According to the principle of color mixing, any color is obtained by mixing the three above. According to the three-color theory, the natural sensation of color is called normal trichromasia.
Clinical picture
Color vision disorders can be congenital or acquired. Anomalies of color vision, which are acquired in nature, are noted in pathologies of the retina, optic nerve, central nervous system, poisoning, intoxication. They are manifested by a violation of the perception of the three primary colors and are accompanied by various visual impairments. These disorders usually change their nature during the course of the disease and during its treatment, while congenital disorders cannot be corrected. Typically, congenital disorders depend on the weakening or complete loss of function, usually of one of the components. This vision is called dichromasia. Pathology of color perception can be inherited.
According to the classification of Chris and Nagel, the following types of color vision are distinguished:
- normal trichromasia;
- abnormal trichromasia;
- dichromasia;
- monochromasia;
Anomalous trichromasia is in turn divided into protanomaly, deuteranomaly, and tritanomaly. Dichromasia is divided into protanopia (partial red color blindness), deuteranopia (partial green color blindness), tritanopia (partial blue or violet color blindness).
Diagnostics
To make a diagnosis, the Ishihara test is performed.
Treatment of color vision anomalies
Treatment is prescribed only after confirmation of the diagnosis by a medical specialist.
01.09.2014 | Viewed by: 6,822 people.- an abnormality of color vision occurring due to the absence of M-cones. With deuteranopia, green, red, and yellow shades merge into a single color. According to research, in those patients who develop deuteranopia, there is a failure and fusion of the mechanisms of perception of the above colors.
Deuteranopia refers to dichromasia - the peculiarity of perceiving images with only two types of cones. Other types of dichromasia are protanopia and tritanopia.
In general, patients with deuteranopia do not distinguish certain colors of the spectrum in the same way as protanopes, but they do not have darkening of the image.
With protanopia, dark shades - purple, violet, burgundy, blue - are similar and practically do not differ from each other. The picture below shows the colors of the rainbow to visualize how people with dichromasia see them.
Pathology refers to diseases that lead to color blindness. It occurs in 1% of men and is often called color blindness.
This term is used in honor of J. Dalton, a man who was diagnosed with the disease after his death (after 1.5 centuries). This event occurred in 1995 during the study of DNA from Dalton's eye, preserved in laboratory conditions.
Color vision anomalies
Ophthalmologists include minor problems and disturbances in determining colors and shades as anomalies. All of them are genetically transmitted according to the autosomal recessive type of inheritance, that is, based on linkage to the X chromosome.
All patients with color vision anomalies are considered trichromats. This means that for such people, as with normal vision, healthy person, to determine the visible spectrum, 3 colors are required.
But people with slight deviations in color perception understand the color gamut somewhat worse than trichromats with good vision.
If you use a special test to compare colors, but they use red and green in different proportions. If testing is performed using an anomaloscope device, then the data reflects the following fact.
With protanomaly, more red is seen, and with deuteranomaly, more green is seen. Sometimes with tritanomaly, the color perception of yellow and blue shades changes pathologically.
Dichromats
Existing types of dichromatopsia are also transmitted genetically through a connection with the X chromosome. The pathology boils down to the fact that the patient can describe all shades only with the help of 2 primary colors. By analogy with deuteranopes and protanopes, in such patients the activity of the green-red channel is abnormally altered.
For example, with protanopia there is no difference between the colors black and red, and descriptions of red are often confused in comparison with brown, gray, and less often with green. Patients see some portion of the color spectrum as achromatic.
With protanopia, this part is from 480 to 495 nm, with deuteranopia - from 495 to 500 nm. Tritanopia develops much less frequently. Such patients do not distinguish between blue and yellow shades.
At the same time, the entire end of the blue-violet spectrum is visualized by them as gray-black. The achromatic spectrum for such people is from 565 to 575 nm.
Complete color blindness
0.01% of the population is diagnosed with a complete lack of perception of the color spectrum. Such people are called monochromats. They distinguish only black and white colors, respectively, they see all objects as gray with different color intensities.
They have impaired adaptation to color changes in the case of photopic illumination. Since the visual organs of patients are instantly blinded, in bright light they also cannot see the shape of objects, which ultimately leads to severe photophobia.
Such people wear glasses with sun lenses in any light during the day. In their retina, ophthalmologists, as a rule, do not detect a single defect.
Disorders of the rod apparatus
In the case of development of defects of the rod apparatus in patients, the function of adaptation to twilight lighting decreases. This phenomenon is called nyctalopia, and it develops against the background of vitamin A deficiency. It is this vitamin that is the basis for the production of retinal.
Diagnosis of color vision disorders
Any anomalies in color vision are transmitted as a trait for which the X chromosome is responsible. In this regard, men are more susceptible to developing pathologies.
Thus, the prevalence of protanomaly among males is about 0.9%, deuteranopia - 1-1.5%, deuteranomaly - 3.5-4.5% (in women - no more than 0.3%), protanopia - 1% (for women - about 0.5%).
Anomalies such as tritanomaly and tritanopia are extremely rare.
Anomalies are usually called certain minor disturbances in color perception. They are inherited as a recessive trait linked to the X chromosome. Persons with color anomaly all are trichromats, i.e. they, like people with normal color vision, for full description visible color three primary colors must be used. However, anomalies are less able to distinguish some colors than normal-sighted trichromats, and they use different proportions of red and green in color-matching tests. Testing with an anomaloscope shows that with protanomaly there is more red in the color mixture than normal, and with deuteranomaly there is more green in the mixture than necessary. In rare cases of tritanomaly, the yellow-blue channel is disrupted.
Dichromats
Various shapes Dichromatopsia is also inherited as an X-linked recessive trait. Dichromats can describe all the colors they see using only two pure colors. Both protanopes and deuteranopes have impaired functioning of the red-green channel. Protanopes confuse red with black, dark gray, brown, and in some cases, like deuteranopes, with green. A certain part of the spectrum seems achromatic to them. For protanope this region is between 480 and 495 nm, for deuteranope it is between 495 and 500 nm. Rarely found tritanopes confuse yellow and blue. The blue-violet end of the spectrum seems achromatic to them - like a transition from gray to black. The spectral region between 565 and 575 nm of tritanopes is also perceived as achromatic.Complete color blindness
Less than 0.01% of all people are completely color blind. These monochromats see the world like a black and white film, i.e. only shades of gray are distinguished. Such monochromats usually show impaired light adaptation at photopic lighting levels. Because the eyes of monochromats are easily blinded, they have difficulty distinguishing shapes in daylight, which causes photophobia. That's why they wear dark ones Sunglasses even in normal daylight. In the retina of monochromats with histological examination usually no anomalies are found. It is believed that their cones contain rhodopsin instead of visual pigment.Disorders of the rod apparatus
People with abnormalities of the rod apparatus perceive color normally, but their ability to adapt to darkness is significantly reduced. The cause of such “night blindness”, or nyctalopia, may be an insufficient content of vitamin A1 in the food consumed, which is the starting substance for the synthesis of retinal.Diagnosis of color vision disorders
Since color vision disorders are inherited as an X-linked trait, they are much more common in men than in women. The incidence of protanomaly in men is approximately 0.9%, protanopia 1.1%, deuteranomaly 3-4% and deuteranopia 1.5%. Tritanomaly and tritanopia are extremely rare. In women, deuteranomaly occurs with a frequency of 0.3%, and protanomaly - 0.5%.NORMAL PICTURE:
Deuteranope (red-green deficiency):
Protanope (another form of red-green deficiency):
Tritanope (blue-yellow deficiency, very rare form):
Keep in mind that these are the LIMITING options shown (well, if there is no sensitivity at all for these colors)
This is such a complicated thing, it turns out.
Want to test yourself?
There are Ishihara tables for testing, selected from random circles so that dichromats (two-color vision) and trichromats (three-color, full) and non...chromats (or whatever they call them, in general complete color blindness) see different numbers/pictures on these test tables.
So I dug up tables from Russian books, look:
Figure 1. All normal trichromats, abnormal trichromats and dichromats distinguish the numbers 9 and 6 equally correctly in the table (96). The table is intended primarily for demonstration of the method and for reference purposes.
Figure 2. All normal trichromats, abnormal trichromats and dichromats distinguish two figures equally correctly in the table: a triangle and a circle. Like the first table, it is intended primarily for demonstration of the method and for reference purposes.
Figure 3. Normal trichromats distinguish the number 9 in the table. Protanopes and deuteranopes distinguish the number 5.
Figure 4. Normal trichromats are distinguished by a triangle in the table. Protanopes and deuteranopes see a circle.
Figure 5. Normal trichromats are distinguished in the table by numbers 1 and 3 (13). Protanopes and deuteranopes read this number as 6.
Figure 6. Normal trichromats distinguish two figures in the table: a circle and a triangle. Protanopes and deuteranopes do not distinguish between these figures.
Figure 7. Normal trichromats and protanopes distinguish two numbers in the table - 9 and 6. Deuteranopes distinguish only the number 6.
Figure 8. Normal trichromats distinguish the number 5 in the table. Protanopes and deuteranopes distinguish this number with difficulty, or do not distinguish it at all.
Figure 9. Normal trichromats and deuteranopes recognize the number 9 in the table. Protanopes read it as 6 or 8.
Figure 10. Normal trichromats are distinguished in the table by numbers 1, 3 and 6 (136). Protanopes and deuteranopes read two numbers instead: 66, 68 or 69.
Figure 11. Normal trichromats distinguish between a circle and a triangle in the table. Protanopes distinguish a triangle in the table, and deuteranopes - a circle, or a circle and a triangle.
Figure 12. Normal trichromats and deuteranopes are distinguished in the table by numbers 1 and 2 (12). Protanopes do not distinguish these numbers.
Figure 13. Normal trichromats read circle and triangle in a table. Protanopes distinguish only a circle, and deuteranopes - a triangle.
Figure 14. Normal trichromats distinguish the numbers 3 and 0 (30) in the upper part of the table, but do not distinguish anything in the lower part. Protanopes read the numbers 1 and 0 (10) at the top of the table, and the hidden number 6 at the bottom. Deuteranopes read the number 1 at the top of the table, and the hidden number 6 at the bottom.
Figure 15. Normal trichromats distinguish two figures at the top of the table: a circle on the left and a triangle on the right. Protanopes distinguish two triangles at the top of the table and a square at the bottom, and deuteranopes distinguish a triangle at the top left and a square at the bottom.
Figure 16. Normal trichromats are distinguished in the table by numbers 9 and 6 (96). Protanopes distinguish only one number 9 in it, deuteranopes - only the number 6.
Figure 17. Normal trichromats distinguish two shapes: a triangle and a circle. Protanopes distinguish a triangle in the table, and deuteranopes - a circle.
Figure 18. Normal trichromats perceive the horizontal rows of eight squares each in the table (color rows 9th, 10th, 11th, 12th, 13th, 14th, 15th and 16th ) as monochrome; vertical rows are perceived by them as multi-colored. Dichromats perceive vertical rows as monochromatic, and protanopes perceive vertical color rows - 3rd, 5th and 7th - as monochromatic, and deuteranopes perceive vertical color rows - 1st, 2nd, 4th, 6- th and 8th. Colored squares located horizontally are perceived by protanopes and deuteranopes as multi-colored.
Figure 19. Normal trichromats are distinguished in the table by numbers 9 and 5 (95). Protanopes and deuteranopes distinguish only the number 5.
Figure 20. Normal trichromats distinguish between a circle and a triangle in the table. Protanopes and deuteranopes do not distinguish between these figures.
Figure 21 missing
Figure 22. Normal trichromats distinguish two numbers in the table - 66. Protanopes and deuteranopes correctly distinguish only one of these numbers.
Figure 23. Normal trichromats, protanopes and deuteranopes distinguish the number 36 in the table. Persons with severe acquired pathology of color vision do not distinguish these numbers.
Figure 24. Normal trichromats, protanopes and deuteranopes distinguish the number 14 in the table. Persons with severe acquired pathology of color vision do not distinguish these numbers.
Figure 25. Normal trichromats, protanopes and deuteranopes distinguish the number 9 in the table. Persons with severe acquired pathology of color vision do not distinguish this number.
Figure 26. Normal trichromats, protanopes and deuteranopes distinguish the number 4 in the table. Persons with severe acquired pathology of color vision do not distinguish this number.
Figure 27. Normal trichromats distinguish the number 13 in the table. Protanopes and deuteranopes do not distinguish this number.
By the way, color calibration on your monitor can play an important role, so the classic result will only be obtained by an ophthalmologist, with calibrated paper tables (or maybe on a monitor that costs a thousand dollars, which is calibrated). And these results are for everyone to know and who are interested. Approximate, in general.
ACROMATOPSY AND MONOCROMATOPSY
Complete absence of color perception, in the first case due to the absence of cones in the retina, in the second, due to the presence of only one type of cones.
DYCHROMASIA
Impaired color perception by retinal elements. It can be congenital, like color blindness, or acquired
COLOR BLINDNESS
A hereditary, less commonly acquired feature, expressed in the inability to distinguish one or more colors.
The etymological origin of the word comes from the name of mathematician and physicist John Dalton, who suffered from this disorder. Distinguish different degrees diseases, the ability to see colors or problems distinguishing between shades of red and green, which can be problematic in everyday life.
This hereditary disease, associated with the X chromosome, so women suffer from it less often. The degrees of the disease are classified according to color perception and degree of perception
In humans, color-sensitive receptors are located in the central part of the retina - nerve cells which are called cones. Each of three types cones have their own type of color-sensitive pigment of protein origin. One type of pigment is sensitive to red, another to green, and another to blue.
People with normal color vision have all three pigments (red, green and blue) in the cones in the required quantities. They are called trichromats.
Monochrome colorblindness
there is only one of the three cone pigments and decreased vision in one color.
Bichromatic color blindness
is a serious deficiency in which there is absence or dysfunction of one of the three major color mechanisms or cones. It can be of three types:
Protanopia
Lack of receptors that identify long wavelengths and perceive red color. Red appears dark beige and green resembles red.
Deuteranopia
This is the most common type of dichromatic color blindness and consists of the absence of receptors that detect the length of the medium wavelengths corresponding to green. Color perception is similar to protanopia, but red colors do not appear as dark.
Tritanopia
Lack of receptors that identify the corresponding short wavelength of blue color. Problems distinguishing between blue and green; difficulty distinguishing may occur yellow color and the perception of red as darker.
In the case when the activity of one of the pigments is simply reduced, they speak of abnormal trichromacy - depending on the color, the sensation of which is weakened, such conditions are called protanomaly, deuteranomaly and tritanomaly, respectively.
Those who suffer from this disease have three types of cones, but with functional defects. Thus they confuse the colors. This is the most common group among color blindness and the effects are similar to dichromatic color blindness, but weaker.
There are three types of dichromatic color blindness:
Protanomaly
Decreased perception of receptors that identify long wavelengths responsible for the color red. The effect of color perception is similar to protanopia, but milder.
Deuteranomaly
This is the most common type of tricolor color blindness and consists of changes in the receptors that detect the medium wavelengths corresponding to the color green. The perceptual effects are similar to protanomaly, but the color red is not as dark. The effect of color perception is similar to deuteranopia, but milder.
Tritanomaly
Decreased perception of receptors that identify short wavelengths of blue light. Difficulty in perceiving blue and green, yellow is similar to red. The color perception effect is similar to trinanopia, but milder.
ACQUIRED DEFICIENCY
Acquired deficiency can occur in both men and women. Most often it appears in only one eye. The most common are those that correspond to altered perception blue color and is observed in the elderly or children.
This may be due to infectious diseases (syphilis) or non-infectious diseases such as cataracts, glaucoma and degeneration macular spot, and excessive consumption of alcohol, tobacco or drugs.
DIAGNOSIS AND TREATMENT
The nature of color perception is determined on special polychromatic Rabkin tables, with images (usually numbers) consisting of many colored circles and dots of the same brightness, but slightly different in color.
Farnsworth test, consisting of colored disks of up to 100 different shades, numbered on the back. The patient must sort them by color.
There is also an anomaloscope - a device using spectral colors that were obtained by decomposing prisms and white. This is a very accurate device that helps detect deficits and levels of color vision impairment.
There are currently many attempts to improve color perception, especially in dyschromats, but they do not produce the same level of perception as in tricromats. Monocular red filters were initially used, but lack of aesthetics and limited effectiveness led to a decline in their use. Later, the use began contact lenses X-Chroma™ and Chromogen™, but neither of them achieved the desired result.
It appears that the information revolution is beginning to provide support programs for color display that may be a solution to color vision disorders in the future.
