Bilateral optic system aplasia with relatively normal eyes.

An infant with extensive CNS malformations and aplasia of the optic system in association with grossly normal-appearing eyes was studied. The neural malformations included partial agenesis of the medulla, pons, and cerebellum and striking maldevelopment of the telencephalon and diencephalon, with lissencephaly, complete arrhinencephaly, and agenesis of the optic system. Because the optic vesicles are outgrowths from the diencephalon, the absence of some structures derived from them is not surprising.