Color blindness: frequency, types and causes of color vision
Color blindness can have different causes. The greatest probability of becoming color blind arises from heredity.
The term color blindness or color blindness is a general collective term for various blurred vision and color vision problems. Color-blind people often have a hereditary Red-green color blindness or even one Red-green color blindness. But not only red and green, but also the colors yellow and blue can be affected. Then one speaks of one blue blindness or one blue amblyopia.
A real and complete color blindness (also achromatopsia called) causes those affected not perceive any colors at all can, so are actually color blind. What is commonly referred to as color blindness is actually a color vision defect where the eyes can not distinguish between different colors (dichromatopsia, also as dyschromatopsie or Dyschromasie designated).
Frequency of color blindness
The color blindness can take on different forms and is therefore common in different frequency, sometimes inheritable. The most common type of color blindness is the red-green weakness associated with a Probability of 5% the total population occurs and preferably men concerns. Within the sexes this color blindness occurs in about 9% of all men and slightly less than 1% of all women. Red-green-visual weakness or blindness is always innate, thus hereditary. The Frequency of green light (deuteranomaly respectively. deuteranopia) is significantly higher than that Frequency of redness (Protanomalie respectively. Protanopie).
The blue blindness (tritanopie) or one blue amblyopia (Tritanomaly) is often referred to as blue-yellow-blindness or blue-yellow-visual impairment. This color vision deficiency is much rarer, with a probability of about 0.005% for tritanopia and 0.005% for tritanomaly, women and men are equally affected in this visual impairment.
The complete color blindness, in which the persons concerned see only shades of gray instead of the shades, occurs in comparison to the above-mentioned color blindness much less frequently.
Color blindness symptoms and causes
People with color blindness or color weakness sometimes do not know anything about their vision disorder, because especially with inheritable poor eyesight, those affected do not know how the colors actually look. Therefore, such visual impairment sometimes only becomes apparent in contact with fellow human beings, for example, when the person concerned buys a supposedly dark red scarf, which is actually pink. It can be dangerous if the person concerned does not correctly recognize red brake lights in traffic, for example.
How does color vision develop??
So that healthy eyes can see colors at all, normal sighted people have different sensory cells on the retina, the so-called cones. Of these cones, there are a total of three different types: one kind takes green light true, others take Red light true and the third kind takes blue light true. By combining these basic colors, all other colors can be recognized. Incidentally, there are no cones for yellow. In the blue-yellow weakness, only the perception of the blue light is impaired.
In people with color blindness, either one species or several species of these cones is defective. Red-green-disturbances occur most frequently, whereby there are still two subspecies with the same result:
- On the one hand, the cones for the color red (long-wave light) may be restricted, functionless or even absent for a red interference. A red-green weakness is called a protanomaly and a red-green blindness is a protanopia.
- However, the cones on the retina may also be restricted, functionless or missing, which should perceive green (medium-length) light. Again, a distinction is made between perfect red-green-blindness (deuteranopia) and red-green-weakness (deuteranomaly).
For a red-green-weakness or -blindness only one of the two forms is necessary, since the two colors can be distinguished only in the mutual contrast.
Genetic causes and heredity
There are various causes for color blindness or color vision deficiency. A common cause is genetic predisposition, within the family multiple members may be color-blind. The cause of the genetic inheritance of defective cones lies in the chromosomes: The genes for the red and green cones are located on the X chromosome, of which the man has only one, while women have two X chromosomes. Therefore, the color vision deficiency also occurs much more frequently in men: If women have a chromosome with the genetic defect, usually no defective vision develops due to the other healthy chromosome, but in man this “alternative chromosome” does not exist.
In contrast to color blindness, which is caused by defective green or red cones, is the yellow-blue disorder only inherited in very rare cases. It usually develops as a result of a disease, such as a macular degeneration, a tumor that presses on the optic nerve or diseases of the retina. A cataract can also lead to color blindness. Here is a list of common eye diseases.
Diagnosis farbblind and test
The colorectal disorder often does not strike the affected person at first. Anyone who has a suspicion in this regard, the ophthalmologist may undergo some color and vision tests that specifically test the various forms of color blindness or color vision deficiency.
In a test for color blindness are often called pseudo-isochromatic plates used on which round color patches are shown in different shades. Normal-sighted people can recognize certain numbers on these tablets, while people who are color-blind do not see those numbers. This test, too “Ishihara color chart test“, But can not determine the specific level of ametropia. For this, further ophthalmological tests are necessary. It is difficult for smaller children, because the color blindness test at the ophthalmologist is quite complicated and can be difficult to do with troubled, young children.
Color blindness test online (also for children)
If you have one for your eyes or with your child Online test for color blindness If you want to investigate a suspicion, you can try this video. This color vision weakness test is also suitable for children. Just follow the instructions together with your child:
Therapy and treatment of color blindness
Since a color blindness may involve significant limitations, the desire for healing and treatment options is great. However, this wish must remain unfulfilled at present; There is no cure for color blindness or color vision, either with medication or surgically. Eye laser surgery can not restore color vision.
Eyewear, which can alleviate the visual impairment, are unfortunately also useless for people who are color blind. Here, only the color contrast, but not the eyesight of the patient is affected. Although the color-blind wearer of the glasses can then differentiate other colors, the deficit only shifts to a different color range. For an eye test these glasses are not allowed.
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