Coloboma

A gap in a structure of the eye present from birth

Overview

A coloboma is a congenital gap in one of the structures of the eye, such as the iris, lens, retina, choroid, or optic nerve. It arises when the optic fissure, a seam on the underside of the developing eye, fails to close completely early in pregnancy. An iris coloboma gives the pupil a keyhole shape, while colobomas at the back of the eye may affect vision depending on their size and location. It can occur in one or both eyes and alone or as part of syndromes such as CHARGE syndrome. Vision ranges from normal to severely reduced.