Red-green vision

Beautiful colorful world. Unfortunately, not all of us see them equally colorful. People with red-green vision impairment find it difficult to distinguish between the two colors. For most, however, this is not a problem. You do not know the world differently. Red-green vision deficiency and color blindness are congenital and occur much more frequently in men than in women.

What is a red-green visual impairment?

What are the causes of a red-green?

It is genetically conditioned, thus innate. The reason: visual pigments in the receptors ensure that they respond to light with certain wavelengths – the visual pigment of the red cones to long-wave light, that of the green cones to light of medium wavelengths.

If the gene for the respective visual pigment is defective, the chemical structure of the pigment changes. The receptor responds less well or no longer responds at all to light. The consequence: The brain can no longer determine exactly which color a visual stimulus had during subsequent visual stimulus processing. If a receptor fails, it is primarily the color discrimination ability that suffers.

Color vision deficiencies can also be caused in the course of life, for example, by diseases or the use of medication. Some affected people then develop a blue-yellow disorder, among other things.

How do people with red-green deficiency see??

Depending on how severely the visual pigments are disturbed, people with a slight red-green deficiency see both colors with few restrictions, while others do not recognize red or green at all and confuse the two colors with each other. Some also don’t know they have red-green deficiency at all. Often only an eye test brings clarity.

People with a green deficiency (deuteranomaly) recognize green tones only to a diminished extent, the color appears dull. Those who have red-green weakness (protanomaly) see red much darker.

Color blindness achromatopsia red-green vision loss protanopia normal vision
Vision with red-green deficiency (color blindness, achromatopsia, protanopia)

Vision with red-green deficiency

Color blindness Achromatopsia Red-green visual impairment Protanopia Normal vision
Vision with red-green deficiency (color blindness, achromatopsia, protanopia)

Operation: Move the sliders back and forth to compare the two visual impressions.

Why do significantly more men have red-green vision defects than women??

The genes for the visual pigments of the red and green cones are located on the X chromosome. Since women are known to have two X chromosomes, a normal X chromosome can compensate for a defect in the second chromosome. Women therefore only develop red-green deficiency if both X chromosomes have a defective gene of the visual pigment.

Men, on the other hand, have only one X chromosome and one Y chromosome. However, there are no genes for the two visual pigments on the Y chromosome and thus no substitute for a defective gene of the X chromosome. Therefore, 9 percent of men and only 0.8 percent of women develop red-green weakness. The green deficiency is the most common color vision deficiency.

What to do when children have red-green vision impairment?

Don’t worry: the visual impairment will not worsen and the child can lead a normal life. However, when school starts, parents should know about their offspring’s color vision deficiency. Because later on, certain jobs such as police officer or pilot are taboo when choosing a profession with pronounced red-green vision impairment.

Is there an eye test for red-green vision deficiency??

One way to determine red-green deficiency is the so-called Ishihara charts: they show many circles of different sizes and colors. People with normal vision can recognize numbers or figures on it, because they are represented by circles, which differ from the other circles by their color tone. People with red-green deficiency have a difficult. They read a wrong number. In addition, there are tests in which those affected have to sort colored platelets or the like according to color.

In addition, ophthalmologists can measure the severity of a red-green deficiency with the help of a so-called anomaloscope. The affected person has to match the color of a test field to the color of a comparison field. Cheating is hardly possible.

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