Wednesday, June 2, 2010


Dichromatism is a type of color deficiency which can be found in three different forms. These three forms are: protanopia, deuteranopia, and tritanopia. These forms of dichromatism are considered to be sex linked because the problem causing this is found on the X chromosome. Being that only one completely normal gene is needed in order to see color properly, women do not tend to have color deficiencies simply because they have two X chromosomes. Males on the other hand have only one X chromosome, making it more likely for the issue to occur. Women are able to carry the trait however and pass it on the their male child.

The first type of dichromatism is called protanopia. This condition affects only about 1 percent of males and .02 percent of females. The wavelenghts in this condition are short and seen as a light blue, before becoming gray. At the point where a person with this condition sees gray, it is considered their neutral point. The wavelenghts which can be found above this neutral point are seen as yellow.

The second type of dichromatism is deuteranopia, which is much like protanopia. This condition affects about 1 percent of males and .01 perfect of females. The perceptions of blue and yellow are the same as protanopia except, the neutral point in this case is seen at 498 nm rather than 492.

Finally, the last type of condition is called tritanopia which only affects about .002 percent of males and .001 percent of females. People who suffer from this condition have a neutral point at 570 nm and are able to see short wavelengths of blue below that point, and long wavelenths of red above that point.

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