A condition known as 'aniridia' has been known since the middle of the last century and many reports have appeared since then.
The term 'aniridia' refers to a apparent absence of the iris, the colored part of the eye that forms the pupil. In many individuals, parts of the iris are visible by inspection but in some it cannot be seen except by special examinations performed by an eye doctor. Aniridia does not always occur by itself but may be accompanied by other eye defects and sometimes by defects in other parts of the body, particularly in the kidney and urinary tract.
Even the simplest form of aniridia can be associated with other significant eye abnormalities. Cataracts, optic nerve defects, corneal clouding, and incomplete development of the retina are frequently present. The most serious problem is glaucoma which may be difficult to treat. Vision varies widely due to the variable nature of the ocular defects.
A significant number of patients with aniridia have other problems as well and for this reason all patients should be examined by an ophthalmologist, an internist, and a urologist. About one-third of individuals have a kidney tumor, called a Wilms tumor, and often other malformations of the urinary tract. Some degree of developmental delay and/or neurological problems can be present as well.
Many cases occur sporadically, that is, without a family history of similar cases. Most of the rest are hereditary and passed from one generation to the next in a pattern known as autosomal dominant. A parent with aniridia can expect that half of his/her children will also have aniridia. Deletions of portions of chromosome 11 may also cause anirida, usually in association with kidney tumors and other abnormalities.
The diagnosis of aniridia may be suspected when the iris is absent or abnormal but the gene mutation may also be present when no evident abnormalities are present. This is a congenital and non-progressive condition. Because of the risk of other organ disease, it is important that all members of families be examined by an ophthalmologist with referrals to internists and urologists as appropriate. Cloudy corneas (windshield of the eye) may impact vision but if the retina is not properly formed, even corneal transplantation may not improve vision. The most serious threat to vision is glaucoma and all affected individuals should have periodic eye examinations throughout their lives. Urinary tract malformations require attention by an urologist.