A case of the morning glory disc anomaly is reported in which alternating contraction and dilation movements were observed and documented with fundus photographs. The movements are attributed to an anomalous communication between the subretinal and subarachnoid spaces that permits flux of fluid to occur between the two compartments, with consequent variation in the degree of retinal elevation within the excavated portion of the lesion. The clinical features of the morning glory disc anomaly, peripapillary staphyloma and optic disc coloboma are presented, and the relationship among these lesions is discussed. The author concludes that the morning glory disc anomaly is a clinical entity distinct from peripapillary staphyloma and optic disc coloboma. It is thought to be due to dysgenesis of the distal optic stalk leading to anomalous persistence of the extension of the cavity of the optic cup into the stalk.