Color vision deficiency (color blindness) refers to abnormal color vision that causes a person to see colors differently than others see them or that causes problems distinguishing certain colors. The deficiency may range from difficulty telling the difference between shades of the same color to total inability to see any colors at all. Most people with this problem have a mild deficiency and have 395
difficulty distinguishing shades of red and green. Eyes
Color vision deficiency is usually an inherited disorder. It is predominant in men, and about 8 percent of all males are affected, although women can carry the gene for defective color vision and pass it to their children. In people with color vision deficiency, receptor cells for color in the retina (the light-sensitive membrane that lines the back of the eye) malfunction, sending incorrect information about color to the brain. The severity of the disorder varies from person to person. Color vision deficiency is diagnosed according to the person's symptoms and the results of color vision testing.
Some people have defective color vision that is not inherited. Aging can cause the lens of the eye to darken, affecting a person's ability to differentiate colors. Certain drugs and eye diseases also can disturb normal color vision.
There is no cure for inherited color vision deficiency, but affected people can take steps to counteract the problem. Some people learn to compensate by developing their own methods of distinguishing different colors—for example, by brightness or location. Tinted prescription eyeglasses may help some people who have red-green color vision deficiency.
If you have a family history of color vision deficiency and work in an occupation that requires distinguishing colors, or if you are having trouble identifying colors, see an ophthalmologist to be tested for color vision deficiency. He or she can recommend steps you can take to compensate for the problem.
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