n. a defect in colour vision in which reds, yellows, and greens are confused. It is thought that the mechanisms for perceiving red light and green light are in some way combined in people with this defect. Compare protanopia; tritanopia. See also colour blindness.
any of various conditions in which certain colours are confused with one another. True lack of colour appreciation is extremely rare (see monochromat), but some defect of colour discrimination is present in about 8% of Caucasian males, and 0.4% of Caucasian females. The most common type of colour blindness is Daltonism (protanopia) – red-blindness – in which the person cannot distinguish between reds and greens. Occasional cases are due to acquired disease of the retina but in the vast majority it is inherited. The defect is thought to be in the functioning of the light-sensitive cells in the retina responsible for colour perception (see cone). See also deuteranopia; trichromatic.... colour blindness
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