Occlusion of a pre-retinal arterial loop.

A CONGENITAL vascular anomaly in which one of the main branches of the central retinal artery forms a pre-retinal loop at the optic disc before being distributed in the normal manner has been described by several authors (Liebreich, 1871; Leber, 1915; Bisland, 1953). The condition is usually first noticed on routine examination of an otherwise normal fundus, and remains symptomless throughout life. Very rarely, however, it may be discovered following occlusion of the affected vessel.