Color blindness can be either hereditary or acquired.
Color blindness is a type of inheritance. Color blindness is inherited through the X chromosome. This influences the fact that color blindness is much more common among men than among women.
For a man to exhibit color blindness, a single maternal chromosome with the color blindness gene is sufficient. And a woman will be color blind only if she simultaneously receives the specified gene from her mother and paternal grandmother. Accordingly, the incidence of color blindness in men is 2-8%, and in women only 0.4%.
Acquired color blindness can occur due to damage to the retina or optic nerve and occurs with equal frequency among male and female populations.
Among the causes leading to it are damage to the retina from ultraviolet light, diabetic macular degeneration, head injuries and the effects of taking certain medicines.
Acquired color blindness is typically characterized by difficulty distinguishing between yellow and blue.
Exists clinical classification color blindness in colors, the perception of which is impaired.
The human retina contains color-sensitive receptors - cones and rods, which contain several types of protein pigments. Rods are responsible for black and white vision, cones for color perception.
Physiologically, color blindness manifests itself in the reduction or absence of one or more pigments in the cones. Based on this, several types of color blindness can be distinguished:
Achromasia(achromatopsia) – lack of color vision. A person can only distinguish shades of gray. It is observed extremely rarely, caused by the complete absence of pigment in all cones.
Monochromacy– a person perceives only one color. The disease is usually accompanied by photophobia and nystagmus.
Dichromasia- the ability to see two colors. In turn, they are divided into:
Trichromasia– perception of all three primary colors. It can be normal, which means there is no color blindness, or abnormal.
Anomalous trichromasia falls between normal trichromasia and dichromasia. If a dichromat does not see the difference between two colors, an anomalous dichromat no longer experiences difficulties with colors, but with their shades - depending on the amount of working pigment in the cones.
In anomalous dichromasia, similarly to dichromasia, protanomaly, deuteranomaly and tritanomaly are distinguished - weakening of the perception of red, green and blue colors, respectively.
In some cases, the inability to distinguish some shades is compensated by increased vision in the perception of others. This way, people who have difficulty distinguishing red from green can see large number shades of khaki, unavailable to most.
Pigment methods.
The most famous pigment method for diagnosing color blindness - using polychromatic ones - has been successfully used from the middle of the last century to the present day.
The tables are filled with multi-colored circles of equal brightness. From circles of the same shade in the pictures, various numbers are made and geometric shapes. By the number and color of the figures identified by the patient, the degree and type of color blindness can be determined.
Also used are more simple tables Stilling, Ishihara, Yustova (the first obtained by calculation, and not by experimental selection of colors), Holmgren's Method (it proposes to sort skeins of multi-colored woolen threads into three primary colors), the method of flickering lanterns.
Spectral methods.
Such studies require the use of special instruments and are therefore used much less frequently. These are Girenberg and Abney devices, Rabkin spectroanamaloscope, Nagel anomaloscope and others.
There are currently no treatments for hereditary color blindness.
Sometimes an attempt is made to correct color perception by selecting special lenses, but this controversial method, and it does not always lead to tangible results.
Acquired color blindness, in some cases, is treated by eliminating the cause that caused it - by stopping taking the medications that caused it, or surgically - in case of cataracts and some diseases of the retina.
IN genetic engineering Research is being conducted to introduce missing genes into retinal cells. The technique is at the stage of laboratory testing.
Color blindness, also known as color blindness, is a vision disorder characterized by a reduced ability to distinguish colors.
In the retina human eye contains two types of photosensitive nerve cells: rods and cones. Rods are responsible for twilight vision, cones are active in daylight and are responsible for color differences. There are three types of cones: L cones, which are sensitive to red, M cones, which are sensitive to green, and S cones, which are sensitive to blue. Color perception disorders occur when the pigment of one or more types of cones is completely or partially absent or nonfunctional.
Color blindness can be congenital (hereditary) or acquired.
Congenital color blindness is caused by the transfer of the X chromosome, most often, from the mother who carries the gene to her son. Since women have the XX set of chromosomes, and the healthy chromosome is always dominant, it compensates for the sick one, and the woman becomes only a carrier of the disease. In men, the chromosomes are combined as XY, therefore, in the presence of a pathological gene, they always become color blind. Therefore, the number of colorblind people among men (8%) is much higher than their number among women (0.4%).
Acquired color blindness may develop as a result of damage to the optic nerve or retina. Also, the occurrence of color blindness can be influenced by age-related changes, taking certain medications and some eye diseases. Thus, cataracts cause clouding of the lens, as a result of which the sensitivity of photoreceptors to color deteriorates. If the optic nerve is damaged, even with normal cone color perception, the transmission of color perception deteriorates. Carrying out nerve impulse to cones is disrupted during a stroke, tumor process, Parkinson's disease.
Color blindness is classified according to the colors whose perception is impaired. The following types of this disease are distinguished:
Trichromasia called the ability to perceive all three primary colors. There is normal and abnormal trichromasia.
Anomalous trichromasia is a cross between dichromasia and trichromasia. With this pathology, a person is unable to distinguish shades of primary colors. Similar to dichromasia, anomalous trichromasia includes protanomaly, deuteranomaly and tritanomaly - weakened perception of red, green and blue shades.
In each specific case signs of color blindness are individual, but there are still certain common features by which pathology can be identified:
Acquired form Color blindness can be eliminated depending on the cause of the disease. So, if problems in color discrimination are a consequence of cataracts, then surgery to remove them can improve color vision. If this problem appears due to taking medications, color vision can be restored by stopping treatment.
Genetic color blindness cannot be cured.
People suffering mild form color blindness - dichromia - learn to associate colors with specific objects and in everyday life are often able to identify colors in the same way as people with normal color perception, although their perception of colors differs from normal.
Several years ago, successful results of correcting color blindness in monkeys using genetic engineering methods were published. The essence of the method is to introduce missing genes into the retina. However, such experiments have not been carried out on humans.
There are also methods for correcting color blindness using special lenses. Recently introduced special glasses with lilac lenses, allowing you to distinguish between green and red colors, helping to improve the vision of people with a form of color blindness.
Colorblind people have significant restrictions: they are not allowed to manage commercial vehicles, they cannot realize themselves as sailors, pilots, or military personnel. Representatives of these professions, as well as some others, are required to regularly check their vision.
In Russia, people with some forms of color blindness can receive driver license certain categories, but with the mark “Without the right to work for hire,” which indicates the possibility of driving transport only for personal purposes.
Color blindness is the complete or partial inability to distinguish color under normal lighting conditions. The disease affects a significant number of people around the world, although in different groups their percentage may vary significantly. For example, in Australia, 8% of men and only 0.4% of women are color blind. In isolated communities where the genetic pool is limited, a large number of people are often born with this deviation, including its rare variations. Such communities, for example, are the countryside of Finland, Hungary, and some Scottish islands. How colorblind people see depends on the individual and the form of his disease. In the United States, about 7% of the male population (almost 10.5 million people) and 0.4% of women cannot distinguish red from green or see these colors differently than other people. Very rarely, the disease spreads to shades from the blue spectrum.
How colorblind people see is due to subtypes of the disease, each of which is caused by certain deviations. The most common cause is a problem in the development of one or more cone-shaped visual cells, which sense color and transmit information to the optic nerve. This type of colorblindness is usually dictated by gender. The genes that produce photochromic substances are contained on the X chromosome. If some of them are damaged or missing, men are more likely to develop the disease because they only have one of this type of cell. Women have two X chromosomes, so usually the missing substances can be replenished. Color blindness can also result from physical or chemical damage to the eye, optic nerve, or parts of the brain. For example, people with achromatopsia completely lack the ability to perceive colors, although the impairments are not of the same nature as in the first case.
In 1798, English chemist John Dalton published the first scientific work on this topic, thanks to which the general public became aware of how colorblind people see. His research " Unusual facts about the perception of colors" was the result of awareness of his own illness: the scientist, like some other members of his family, did not see shades from the red spectrum. Colorblindness is generally considered a mild disability, but in some cases it offers certain benefits. Thus, some researchers have concluded that those suffering from color blindness are better able to distinguish camouflage. Such discoveries may explain the evolutionary reason for the high prevalence of color blindness in the red and green spectrum. There is also research suggesting that people with some types of the disease are able to see colors that others cannot see.
To understand how colorblind people see colors, it is necessary to consider the mechanism of perception in general view. The normal retina of the human eye contains two types photosensitive receptors, the so-called rods and cones. The former are responsible for vision at dusk, while the latter are active in daylight. There are usually three types of cones, each containing a specific pigment. Their sensitivity is not the same: one type is excited by a short wavelength of light, the second by a medium wavelength, and the third by a long wavelength, with peaks in the blue, green and yellow regions of the spectrum, respectively. It is assumed that together they cover everything visible colors. These receptors are often called blue, green and red cones, although this definition is not precise: each type is responsible for the perception of a fairly wide range of colors.
IN clinical picture There is a distinction between complete and partial color blindness. Monochromasia, complete color blindness, is much less common than the inability to perceive individual shades. The world through the eyes of a colorblind person with this disease looks like a black and white movie. The disorder is caused by a defect or absence of cones (two or all three), and color perception occurs in one plane. Regarding partial color blindness, from the point of view clinical manifestations There are two main types of it, associated with the difficulty of distinguishing between red-green and blue-yellow.
There are two types in this classification hereditary disorder color perception: dichromasia and anomalous trichromasia. Which colors colorblind people cannot distinguish depends on the subtypes of the disease.
Dichromasia is a disorder of moderate severity and consists of improper functioning of one of three types of receptors. The disease occurs when a certain pigment is missing, and color perception occurs in two planes. There are three types of dichromasia based on which type of cone cell is not working properly:
Want to know how colorblind people see? A photo can give a clear idea of the features of their picture of the world.
This is a common type congenital disorder color perception. Anomalous trichromasia occurs when the spectral sensitivity of one of the pigments is modified. The result is a distortion of normal color perception.
The Ishihara test contains a series of images consisting of colored spots. The figure (usually Arabic numerals) is embedded in the drawing as dots of a slightly different shade, which can be distinguished by people with normal vision, but not with a disorder certain type. Full test includes a set of images with various combinations to reveal whether the disorder is present and specifically what colors colorblind people cannot see. For children who do not yet know numbers, drawings with geometric shapes (circle, square, etc.) were developed. Diagnosis of anomalous trichromasia can also be made using an anomaloscope. Currently, there is no effective treatment for color blindness in humans. Colored lenses may be used to improve the ability to see some colors but make it more difficult to see others correctly. Scientists are conducting trials to treat color blindness using genetic engineering methods, which have already given positive results in a group of monkeys.
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Color blindness is the complete or partial inability to distinguish colors.
This pathology is mainly hereditary and is transmitted from women to men.
We will consider below what colors a colorblind person cannot distinguish.
There are two types of color blindness: complete and partial.
Caused by the absence or improper development all three types of cones. At the same time, a person sees everything in black and white. As already mentioned, such an anomaly is extremely rare;
Partial is divided into the following types:
2. Anomalous trichromasia. This is a condition in which a person's ability to perceive one primary color is reduced (but not completely lost). Similar to dichromasia, there are three types of disorders: protanomaly, deuteranomaly and tritanomaly.
The frequency of occurrence of each anomaly is presented in the diagram:
Depending on the reason for the appearance color blindness happens:
Now let's look at how colorblind people see colors, depending on the type of colorblindness.
Protanopia occurs when red cones are absent or damaged.
This is a hereditary abnormality that affects approximately 1% of all men. At the same time, red colors appear dark gray to a person, violet colors do not differ from blue ones, and orange colors appear dark yellow.
Caused by the absence or improper functioning of green cones.
A person cannot distinguish the green spectrum from yellow and orange. The red color is also very difficult to distinguish.
The video below shows how colorblind people with deuteranopia see.
An extremely rare type of color blindness in which there is no blue pigment. Occurs when the seventh pair of chromosomes is damaged. At the same time blue appears green, purple appears dark red, and orange and yellow appear pink.
This type of color blindness is caused by congenital anomalies cone development. Manifests itself in a modification of the spectral sensitivity of pigments, which manifests itself in a distorted perception of colors.
That is, if dichromats do not distinguish colors at all, then anomalous trichromats have difficulty interpreting their shades.
At the same time, the inability to distinguish some shades with anomalous trichromasia is compensated by an increased perception of other shades. For example, people with protanomaly (the inability to distinguish between shades of the red and green spectrum) distinguish shades of khaki much more clearly. This is not typical for most people with normal color perception.
If color blindness is inherited, cure it with medicines, folk remedies or other methods is practically impossible. If the cause of color blindness is an eye injury, then it is possible to cope with it.
But, in any case, color blindness is not a death sentence. There are remedies that can help partially compensate for this problem:
The inability to see colors can be compensated for by observing other people's actions. You can rely on the brightness or location of the object, in which case color detection is not needed.
Also, knowing certain things, such as the arrangement of colors at a traffic light, will make life much easier and help you cross the road without difficulty.
Considering all of the above, it becomes clear that colorblind people experience certain restrictions in their social activity. Colorblind people cannot work as sailors, pilots, chemists, military personnel, designers and artists.
Contrary to popular belief, colorblind people can get a license and drive a vehicle. However, the document must indicate that the person cannot work as a driver for hire.
In everyday life, colorblind people face many other difficulties:
You can take a color perception test.
Most famous person with color vision impairment is John Dalton. It was he who, back in 1794, began to describe this pathology, based on his own feelings.
For some individuals, color blindness has not become an obstacle to creativity. These include the famous artist Vrubel. His paintings lack green and red shades; they are all painted in pearl gray tones.
French painter Charles Meryon He was also colorblind, which did not prevent his graphic creations from captivating viewers with their beauty.
It is unknown how the life of the famous singer would have turned out George Michael, if not for color blindness. Since childhood, the artist dreamed of becoming a pilot, and after it was discovered that he was color blind, he began to study music.
Also a famous director is colorblind Christopher Nolan, which did not prevent him from achieving world fame.
Several images of what colors colorblind people see and what the world around them looks like.
