Coloboma

A coloboma (from the Greek koloboma, meaning defect,) is a hole in one of the structures of the eye, such as the iris, retina, choroid or optic disc. The hole is present from birth and can be caused when a gap called the choroid fissure between two structures in the eye, which is present during early stages of prenatal development, fails to close up completely before a child is born. The classical description in medical literature is of a key-hole shaped defect. A coloboma can occur in one or both eyes.