How can a person see, yet not see in color? What is color blindness and how does it work? Color blindness, or color vision deficiency, as it is also called, is the inability to distinguish colors and shades. This disorder varies in degrees from trouble distinguishing shades of the same color all the way to the inability to distinguish any colors at all. The latter is extremely rare, and is congenital. Only 8% of males and 1% of females display this type of color vision deficiency.

The most common cause of color blindness is a genetic defect. It is known that the defective gene is carried on the X chromosome, so males are almost exclusively the victim, and white males make up practically the entire percentage of victims. Females, however, are typically the carriers of the defective gene, so males get the defective gene from their mothers. So for the male who has color blindness, if he has a daughter, she will be a carrier of the defective gene, and her sons will have a 50% of being color blind, and her daughters will most likely be carriers. If he has a son, he will not have colorblindness. The color blind man's sisters have a 50% chance of being a carrier and her sons will have a 50% of being color blind. Most types of color blindness are hereditary, however there are some types that are not hereditary. With the aging process, there is aging of the lenses of the eye, which cause them to darken. Retinal and optic nerve diseases, and even some medications can cause this effect, as well.

There is no cure for color blindness. But, people can be taught to recognize colors by means such as brightness of colors or location. An example of the location would be a stoplight. The person would be taught that the red light is at the top, the yellow in the center and the green at the bottom. Another would be to learn that a stop sign is red, a yeild sign, and so forth. Sometimes, specially tinted eyeglasses can help. Check with your ophthalmologist if you suspect you are color vision deficient, to see which of these devices would be right for you.

Color blindness is essentially a defect. It is caused by a defect in the retina or the nerves of the eye. The first documentation of this disorder was made by a British Chemist named John Dalton, who did, in fact, suffer from this disorder. Total color blindness in which all color is seen as shades of gray, only, is called achromatopsia or monochromatism, is extremely rare. More common is partial color blindness. This type is technically termed dichromatism. It consists of the inability to differentiate between reds and greens and sometimes may involove blues and yellows. In the back of the eye, there are rods and cones. The cones pick up the color and the rods control the brightness, sort of like the knobs on your television. There are different cones for different colors. People with color vision deficiency have fewer of some cones than others, that is why there are different variations and degrees of color blindness. Some people may be more color blind than others. Being color blind does not effect your ability to get a driver's license. Most people with color blindness have good vision otherwise. However, some work such as policemen, medical personnel, firemen and transportation workers cannot be color blind for safety reasons and those applying for these jobs usually have to take a test for color blindness. Color blind people accomodate their deficiency in other ways, as afore mentioned, so one interesting tidbit is that they look for contour and outlines, not colors so they don't have problems with camoflauge. In World War II, color blind soldiers were used in spy planes to spot camoflauged German camps. They also usually have exceptionally good night vision. If you have trouble distinguishing colors, check with your eye doctor for testing or find some neat, simple tests online.