Aniridia is a rare medical condition affecting the eyes. It is congenital (present at birth). Most people with aniridia have all or part of their irises (the coloured rings in the eyes) missing which is what gives the condition its name. It also causes many parts of the eye to be under-developed, such as the optic nerve and macular/fovea. This results in most people with aniridia having some reduction in their level of vision.
People with aniridia may also develop other eye conditions. Aniridia and these associated conditions affect everyone differently. So while some people with aniridia are partially sighted or blind, others may have near normal sight.
Aniridia is a genetic condition. It is usually due to an abnormality in a gene called PAX6. This can be inherited from a parent or be a result of a mutation when a baby is conceived. Read more about the genetics of aniridia.
Aniridia may also occur among other conditions as part of another genetic condition known as WAGR/11p Deletion Syndrome.