albinism

Rare hereditary condition in which the body lacks tyrosinase, one of the enzymes that form the pigment melanin, normally found in the skin, hair, and eyes. As a result, the hair is white and the skin and eyes are pink. The skin and eyes are abnormally sensitive to light, and vision is often impaired. The condition occurs among all human groups and across the animal kingdom.

Albinism may be partial, with irregularly shaped white patches on the skin or hair, or complete, when the entire surface is unpigmented, including the hair and the choroid coat and iris of the eye. The iris appears pink because its transparency in the absence of pigment allows the blood in the small vessels of the retina to show through. This transparency of the iris constitutes a disability in sunlight. At night, however, albinism gives enhanced vision because a greater amount of light reaches the retina.