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Poor Color Vision |
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Poor color vision
Poor color vision is an inability to distinguish between certain shades of color. Although most people call it colorblindness, true colorblindness describes a lack of color vision. The ability to see only shades of gray is rare. Most people with poor color vision can't distinguish between certain shades of red and green in dim light. Some people can't distinguish between red and green shades even in bright light. Less commonly, people can't distinguish between shades of blue and yellow. Poor color vision is an inherited condition in most cases. However, eye diseases and the effects of some medications also can cause color deficiency. About 8 percent of men and 1 percent of women have a deficiency of color vision. Causes Your ability to see colors across the spectrum begins with your eyes' ability to accurately distinguish three primary colors — red, blue and green. Light enters your eyes through your lens and passes through the transparent, jelly-like main body of your eye (vitreous body) to color-sensitive cells (cones) in your retina at the back of your eye. Chemicals in the cones distinguish among colors and send information through your optic nerve to your brain. If your eyes are normal, you're able to distinguish hundreds of blends of colors. If your cones lack one or more light-sensitive chemicals, you may see only two of the primary colors. The most common color deficiency is an inability to see red and green. Instead of a normal spectrum, a person with red-green color deficiency will have one or two neutral or gray areas where these two colors normally appear. Often, a person who is red-green deficient doesn't completely screen out both colors. Defects can be mild, moderate or severe, depending on the amount of light-sensitive substances missing from the cones. Also, a reduced sensitivity to red is seldom equal to a reduced sensitivity to green. Therefore, more people struggle to see green than to see red. Interestingly, most people with red-green deficiency aren't aware of their problem. To them, leaves are green and roses are red, but they might not see the same colors as people with normal color vision. Their "green" may be what normal-sighted people call "yellow," but because they've always heard leaves called green, they interpret what they see as "green." Poor color vision has several causes:
Poor color vision > 1 > 2 > 3 > 4
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