UNUSUAL COLOBOMA OF THE OPTIC NERVE ENTRANCE

Abstract

DEVELOPMENTAL anomalies of the eye in the region of the optic disc are commonly divided into two groups: those in which failure of coaptation occurs within the optic nerve sheath and those showing lesions of the peri- papillary choroid or sclera. With the exception of the small holes sometimes seen on the anterior surface of the optic disc, which are probably related to aberrant formation of Bergmeister's papilla, the first type is much the less frequent of the two, and probably all the anomalies in the second group are formed by imperfect closure of the foetal fissure with the result that they appear on a line running inferiorly from the rim of the optic disc to the equator.