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Protanopia

 
, medical expert
Last reviewed: 12.03.2019
 
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To see the world in colors allows our visual system's ability to perceive waves of light radiation of various lengths, corresponding to colors and shades, and transform them into a holistic sense of a color picture of the surrounding reality. People who do not distinguish colors are called color blind. This is common knowledge. And protanopia? What it is?

Color blindness or light sensibility disorder is a collective term. It turns out that it is also possible to distinguish colors differently. Full color blindness, when a person sees the world as in a black and white photo, is called achromasia. This pathology of color vision is rare. More often the person does not perceive light radiation of a certain range. Protanopia - the lack of perception of the longest waves, perceived as a spectrum of shades of red. Instead, the protanopes see gray of different saturation. The weakening of the perception of shades of red - protanomaly.

The name comes from protium, the lightest isotope of hydrogen, which has a red spectrum of light wave emission.

This is the most common type of color disturbance. D. Dalton, who first began to study and describe him at the end of the 18th century on the example of his family members, suffered from just such a visual impairment. Color blindness, from his light hand, began to call any congenital disorders of color vision.

The inability to perceive medium-wave radiation (deuteranopia) is quite common - a person does not feel the green range of shades. Much less often, color blindness occurs in the shortwave range from blue to violet (tritanopia).

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Epidemiology

The prevalence of color blindness is small, the complete lack of color vision is recorded in one out of ten thousand people on the planet. Some deviations of color perception are present in approximately 8% of the population of the planet with white skin of a male and in 0.5% of women. Moreover, three quarters of cases do not concern the absence, but the weakened perception of the red or green part of the spectrum.

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Causes of the protanopia

In most cases, color blind people are born, most often with protanopia. Genetic mutations are associated with the X chromosome. Inheritance occurs mother to son. In women who have a pair of X chromosomes from the mother and father, visual impairment develops only in the case when both of them have a defect, and this does not happen too often. Basically, when mother and father have each other, though distant, but blood relatives. Men, having received the X chromosome from the mother carrier of the defective gene and not possessing a healthy spare, suffer from different forms of color blindness.

Much less likely to become color blind. Acquired protanopia develops in this case more often only in one eye, where, as a result of a previous illness or injury, the retina or optic nerve was affected.

With age, the development of retinopathy, cataracts, or macular dystrophy blunts the perception of the color palette.

Other risk factors for the development of secondary protanopia include stroke or coma, parkinsonism, eye and brain tumors, long-term drug therapy (pathology is often reversible), exposure to toxic chemicals.

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Pathogenesis

Color blindness develops when the photosensitive cells of the retina, the cones, are damaged, thanks to which the image we see is transformed into a nerve impulse transmitted to the brain, where a colorful perception of the seen is formed. Cones are responsible for daytime color vision.

At present, in the theory of vision, the three-component hypothesis of our color perception prevails, according to which the cones of the eyes are excited to varying degrees under the influence of light waves of different lengths corresponding to red, green and blue. They possess such properties due to the content in them of a biologically sensitive color pigment - iodopsin. According to the three-component theory, it can be of three types: erythrolab is sensitive to red shades, chloro-labore is green to green, cyanolab is blue to green. Moreover, the first two species have already been found, the third is still looking for, but they have already invented a name for it. According to this theory, people with protanopia lack eritrolab or very few erythrolabs or cones mainly with this pigment, which does not allow them to distinguish shades in the red part of the spectrum. Accordingly, deuteranopes do not have enough chloro-lab.

But there are discrepancies regarding blindness in the blue part of the spectrum. While supporters of the three-component hypothesis are looking for cyanolab in cones, supporters of a different view on the formation of color vision (a two-component theory) suggests that the cones contain erythrolab and hlororub simultaneously, but rods are responsible for the perception of the blue part of the spectrum. The faded pigment rhodopsin, contained in the rods, responsible for good vision in the dark, serves as cyanolab. This theory is supported by the fact that people who do not distinguish between blue shades also suffer from night blindness, that is, they do not see well in the dark, in contrast to protanopes and deuteranopes.

In any case, only photosensitive cells are related to protanopia - cones and insufficiency (absence) of erythrolab pigment in them.

trusted-source[10], [11], [12], [13], [14], [15], [16]

Symptoms of the protanopia

A congenital disorder of color perception, especially a partial one, is discovered by chance, since it usually doesn’t bother a person. There is no pain, normal vision, the color in the distinguished spectrum of a person sees the same from the very birth and he was unaware that someone sees them differently. Of course, if the child constantly draws the gray sun or yellow leaves on the trees, you should watch him and possibly reduce him to an ophthalmologist. Although it may be a manifestation of children's imagination. By the way, D. Dalton discovered a protanopia at 26 years old. Until that time, she did not bother him at all.

Another thing is the acquired lack of color perception, in which case the patient begins to see colors differently than before, and, of course, immediately pays attention to this.

Protanopia and deuteranopia - the non-perception of the red or green parts of the color palette. Such dichromacies are among the most frequent features of color sensitivity. At the same time, the protanop can distinguish green from blue and even from dark red, but magenta (a mixture of blue and red) cannot turn blue. To determine the form of color blindness, you need to turn to specialists who have at hand a tool for testing color perception.

Partial anomalies of color vision, when the activity of one of the color pigments is only reduced, are even more common. The most common is deuteranomalia, when chlororuba activity is weakened, and a person does not perceive some shades of green, for example, does not see the difference between light green, olive and turquoise, however, it can distinguish green from red, yellow or blue.

If a person does not distinguish purple from crimson and pink, however, he sees them as red, that is, he still differs in three primary colors, then he most likely has protanomaly - the erythrolab activity in cones is reduced. But, nevertheless, tricolor vision is present.

If you have diagnosed protanopia, then getting a driver's license even for personal use (without the right to work for hire) is unlikely to work out. In the XXI, the rules for issuing rights to people with color perception disorders have become tougher. Even protomanalya is currently an obstacle to obtaining a driver's license. Although the final word for the oculist.

To diagnose dichromatic disorders of color perception, including such as protanopia, there is a Rabkin test - special pictures with the so-called color cipher. Normal trichromats do not need to answer the question of what they see in the picture. People with deviations in color sensitivity usually cannot see the encrypted images on these pictures.

The US military uses Ishihara plates to diagnose color perception disorders. There is also a device for detecting anomalies of color sensitivity - an anomaloscope. To install such a diagnosis should be specialists.

Who to contact?

Treatment of the protanopia

Color blindness (protanopia) as a congenital pathology is incurable. At the present level of medicine, even the causes of such disorders are being studied. Acquired defect can be corrected and in some cases eliminated. Treatment and its success depends on the underlying pathology that caused the disturbance of color perception.

They have not learned to treat congenital pathologies, but they are trying to help people with color perception. Scientists and doctors are trying to return to people all the colors of the world.

For example, you can turn on the computer protonopiya color blindness mode. This color filter is addressed to people who can hardly distinguish between red and green colors. They can be configured in the "Special features" option. When the filter is turned on, the previously mixed colors become more distinct and distinct.

In addition, special glasses are meant for color blind people, and the manufacturers position them not just as coloring, but as dividing light waves. At the beginning, this optical device was generally recommended as glasses for protanopia, however, they can, as well as help with a different form of color perception, and not come up with protanopy. Judging by the reviews, the sensations from the glasses are very individual, therefore they cannot be called a panacea. The most authoritative and expensive brand is Enchroma corrective glasses, and the budget option is Pilestone.

Any glasses need to try on, getting used to the glasses does not happen immediately and takes from several hours to several days. About a tenth of users did not recognize any effect from the use of glasses. However, other correction methods for color blindness, besides those listed above, have not yet been invented.

In conclusion, I would like to note that many successfully adapt to their particular vision, it does not cause them any trouble. People do not even have an idea of their form of color blindness, they simply live and are not going to do anything.

Note:

Protanopia: Wikipedia (the free Internet encyclopedia) briefly and clearly describes this type of color sensitivity disorder in the Color Blindness section.

The comic book "Protanopia" released a multiplier from Thailand. Product with moving pictures for iPhones and Intenet-tablets. The pictures in this application are moving, not only in the plane, as we used to see in cartoons, but also in three-dimensional space. This is achieved by tilting the device in different directions. The next achievement of computer animation is not a test for the presence of color blindness and is not directly related to this pathology of vision.

It is important to know!

With this anomaly, either the absence of the OPN1SW type S-flasks in the retina, or their genetically determined dystrophy, or a pathological change in the structure of the photopigment of iodopsin sensitive to the blue light spectrum is noted.

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