Colorblindness is an eye disorder in which there is an insignificant amount of specific cones in the retina and pigments in the nerve cells of the eye. It is an inability to see or distinguish certain colors, and colorblindness usually comes in varieties like red-green or blue-yellow. A person with red-green colorblindness often cannot distinguish the difference between the colors red and green; for example, they might wear one red sock and one green sock, and not know that they don’t match—they look the same or very similar to the person with the disease.

Colorblindness is an X-linked disease, meaning it is most often given to a son from a mother who carries the disease. A male has one X and one Y chromosome, each of which are very different. If he happens to get the bad X chromosome from his mother who has two X chromosomes, the Y chromosome cannot correct or cover the disorder.
Colorblindness may also be an effect of aging or injury, and sometimes certain medicines may cause colorblindness, such as hydrochloroquine.

Symptoms of colorblindness include not being able to color-coordinate, such as putting an outfit together, like mentioned above in Description, or when coloring a picture—at a young age, odd color schemes of drawings often give away that the child has colorblindness; instead of coloring a red barn and green grass, they might color a green barn and red grass, if they have red-green colorblindness. It is also difficult for people with colorblindness to distinguish shades of a color. A person with colorblindness may also have rapid eye movement, but usually only in severe cases.

Daily Life:

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Colorblindness is diagnosed through eye exams or the
Ishahara Color Blindness Test, where a number or letter of a certain color is placed inside a circle of a different color; for example, for red-green colorblindness, one might have to try to distinguish a green six inside of a red circle. If they cannot, it is more than likely that they have red-colorblindness. Colorblindness is often noticed at a young age when coloring pictures like mentioned above in Symptoms and when dressing independently.

Though colorblindness cannot be completely cured yet, specially tinted contacts or glasses lenses may help one see the colors they usually could not without the contacts or lenses. However, this may limit their ability to see colors that they normally would
without// the lenses. Some medicines may help alter the disorder, though it cannot completely restore one’s ability to see certain colors. Colorblindness cannot be improved, and can only be adjusted with tinted or colored lenses.

Colorblindness is not curable, though vitamin A has been said to help as well as, for example, red and green lenses for red-green colorblindness. More research on how colored lenses affect colorblindness is being conducted.
An experiment done with two male colorblind monkeys has shown that injecting a virus containing the L opsin gene over the retina restored normal vision in the monkeys, who had red-green colorblindness.

Additional Facts:
One in ten men and about 0.5% of women are born colorblind, but since it is an X-linked disorder, mostly males have it, and females that have it are only carriers of the disease and are not affected. A person in any ethnicity can inherit colorblindness, and there is no greater probability with one background or another. Red-green colorblindness is the most common, though there is also blue-yellow colorblindness, which is not X-linked, and is equally common in both men and women. The most severe type of colorblindness is achromatopsia, where one can see no color at all; however, this is usually due to injury or is a side effect of medication, and people are very rarely born with it.

Punnett Square:

Pedigree Chart: