Aniridia
Aniridia is a congenital eye defect characterized
by the partial or complete absence of the iris, the part of the eye that
controls the amount of light reaching the retina. It is often associated with
poor development of the cornea, lens, retina and optic nerve, therefore it is
associated with reduced optical properties.
Aniridia manifests
itself in combination with nystagmus, amblyopia and sometimes mental
retardation. Eyes affected by the absence of the iris are extremely photophobic
and find it difficult to adapt to sudden changes in lighting conditions. This
defect can be most effectively corrected by contact
lenses.