Fundoscopy of the right eye of a patient with a coloboma of the macula, the central region of the retina, the light-sensitive layer at the back of the eye. A coloboma is an area where the normal tissue is missing . It is a rare defect of the eye that is congenital (present from birth). Macular coloboma causes loss of vision in a specific location in the field of sight. There is no treatment for macular coloboma.