Post #3

ALBINISM

Albinism (meaning "white," also called achromia, achromasia, or achromatosis) is a disorder characterized by the complete or partial absence of pigment in the skin, hair and eyes. The disorder occurs due to lack-of or malfunction of tyrosinase, an enzyme involved in the production of melanin. 

The symptoms of albinism related to the eyes include: 

• Rapid, involuntary back-and-forth movement of the eyes
• The inability to direct both eyes at the same point or to move in unison
• Extreme nearsightedness or farsightedness
• Sensitivity to light 

Albinism can occur in people as well as animals. The simptoms are most often white hair, and skin pigmentation ranging from white to brown. The lack of pigment in the irises make they eyes somewhat translucent, which means that the irises can't completely block light from entering the eye. This is why albinos with very light colored eyes may appear to have red eyes in some lighting. This is because you're seeing the light reflecting off the back of the eye and coming back out through the iris again - similar to the red-eye that occurs in flash photography.

Albinism is caused by a mutation in the melanocytes, the cell the produces melanin. In some types of the albinism, a person must inherit two copies of the mutated gene - one from each parent - to have the disorder. There is no cure for albinism, however surgery can be performed on the muscles of the eye to regain normal eye movements (surgery occurs very rarely).

Here are some images of animals affected with albinism: