It is a congenital and hereditary disease. Although the word "aniridia" literally means "lack of the iris of the eye", it is really an eye disorder in which various parts of the eye are involved. It is usually bilateral (both eyes), and incomplete, since in most cases there is an incipient iris which has failed to develop.
The iris is the colored ring of the eye surrounding the black pupil. It is a contractile membrane behind the cornea and in front of the clear lens ( crystalline ), which contracts or expands, opens or closes, depending on the intensity of light that exists in the environment. Its function is to regulate the amount of light that must enter in the ocular globe and reach the retina.
The external appearance of the eye that suffers from aniridia is a big black central pupil, and in most of the cases a small colored strip.
For more information please visit the Spanish Association of Aniridia website at www.aniridia.com.