Unilateral Optic Nerve Entrance Coloboma: The Broken Disc Anomaly

A 30-year-old man presented with poor vision in his right eye since childhood. Funduscopic examination revealed a congenital optic disc anomaly that was atypical in appearance, but most likely a variant of optic nerve coloboma, the entrance coloboma, in which the defect is limited to the junction of the optic nerve and its sheaths with the sclera alone. The primitive choroid was found to traverse the colobomatous cavity in a horizontal manner, giving it a broken disc appearance. Photographic and optical coherence tomographic documentations punctuate the case report and emphasize the rather rare nature of this disease entity.