“…difficulties, he attempted to classify colobomata of the optic nerve under three heads: (1) where the lesion is a coloboma of the choroid beneath the nerve, the nerve itself being normal and sharing only passively in the deformity; (2) where the lesion is a coloboma of the choroid and the nerve; (3) where the lesion is a coloboma of the nerve alone, the adjacent choroid being normal. Parsons and Coats (1906)reported a variation of type (3), in that, as well as there being retina in the optic nerve, the lamina cribrosa had given way at its temporal margin where an ectasia of the retina had occurred. TIhe scleral margin was involved also at this point.…”