Aniridia (Greek) literally means “absence of iris” (the colored part of the eye); however, this is a misnomer because patients with aniridia always have irises that are rudimentary or not fully developed. Years ago when this eye condition was given the name “aniridia,” it was not known that the name would come to only describe the most physically noticeable aspect of the condition. Today it is known that the lack of iris is only a minor aspect of aniridia, and it does not reflect the more important aspects of aniridia that can cause even more vision loss. Aniridia has been and still is referred to as a “rare” eye condition, even though the eye conditions that make up aniridia are common ones such as glaucoma, cataract, corneal degeneration, and low vision. The “rare” aspect of aniridia is having the combination of these conditions in one individual, affecting his or her vision. Aniridia is a genetic eye condition that is congenital—that is, it is present from birth—and affects various structures of the eye. It occurs when the gene responsible for eye development, the PAX6 gene (located on the eleventh chromosome), does not function correctly. The result is developmental disorders not only of the iris, but also of the cornea, the angle of the eye, the lens, the retina (sensory part of the eye), and the optic nerve (nerve that carries visual impulse to the brain). The degree of maldevelopment differs from one patient to another. Aniridia is a bilateral disease. The incidence of this condition ranges from one in 40,000 to one in 50,000 births. It occurs equally in males and females, and has no racial predilection. Aniridia can be familial or sporadic (occurs spontaneously, not inherited). Familial Aniridia (87%): The Ocular Manifestations Occur in Isolation 85% autosomal dominant 2%autosomal recessive has been observed in the rare Gillespie’s syndrome, in which aniridia is associated with cerebellar ataxia, structural defects in the cerebellum and other parts of the brain, and mental retardation. Patients with Gillespie syndrome are not predisposed to the development of Wilms’ tumor.