is a condition in which the iris in one eyes has a different color than the iris of other eye. The iris is the tissue of the eye that surrounds the pupil and imparts a color , wither green, blue, brown, hazel, grey, or other, to the eye . It may be inherited or caused by genetic mosaicism, chimerism, disease or injury . It occurs in humans and certain breeds of domesticated animals. It is caused by variations in the concentration and distribution of melanin , the pigment that gives color to the skin, hair, and eyes .