Many people believe that failing a color blindness test means a person sees things like a black and white movie. However, being color blind usually does not mean a person can't see any color at all. It simply means that he has trouble distinguishing between colors. For example, a person who is color blind may have trouble distinguishing between the green leaves, the red apples, and the brown branches of a tree. In technical terms, a more accurate name for color blindness would be color vision deficiency.
One of the most common tests for color blindness is known as the Ishihara test. This simple test, developed by Japanese ophthalmologist Shinobu Ishihara, asks the subject to identify numbers that are printed as a series of colored dots on a dotted background of a different color. For example, the number 5 might be featured in green dots on a red, orange, and yellow dotted background. If the subject can see both red and green clearly, he will have no trouble identifying the number in this part of the color blindness test.
Most color vision problems are genetic and present when a child is born. Color blindness is much more common in men than women and more common among Caucasians than members of other ethnic groups, with 8 to 10 percent of Caucasian men having some form of color blindness. Among Caucasian women, only 0.5 percent will fail a color blindness test. Total color vision deficiency, in which a person can only see shades of gray, is very rare.
It is important to take a color blindness test during the early childhood years because not being able to identify colors can cause a child to have difficulties with schoolwork. Even something as simple as having the teacher write with yellow chalk on a green chalkboard can make schoolwork frustrating for a color blind child who is unaware that he sees things differently than his peers.
Color blindness can't be treated or corrected, but people who are color blind generally learn to accommodate for the condition quite easily after they are made aware of the problem. For example, the majority of people who are color blind have trouble distinguishing between red and green. When they learn how to drive, they simply memorize the position of the colors on a traffic light in order to work around this issue.
While color blindness is a form of vision deficiency, it does not affect a person's ability to pass a standard eye test. A person who is color blind is no more or less likely to need corrective lenses than someone who is not color blind. There have been studies indicating that people who are color blind actually have slightly better night vision than people who are not color blind.
