Coloboma is a congenital eye defect that occurs when the embryonic fissure fails to close completely during early development. This results in a cleft or gap in structures such as the iris, retina, choroid, or optic nerve. Iris coloboma often appears as a keyhole-shaped pupil, while retinal or optic nerve colobomas can significantly affect vision. Severity varies widely—from minimal visual impact to serious impairment depending on the tissues involved. Coloboma may occur alone or as part of genetic syndromes like CHARGE.