Bilateral optic nerve aplasia associated with hydranencephaly.

A case of bilateral optic nerve aplasia (ONA) associated with hydranencephaly and other multiple congenital anomalies in an infant is reported. Its occurrence in an offspring of a consanguineous union may implicate an autosomal recessive transmission. A brief review of ocular embryology is presented in relation to the possible pathogenesis of bilateral ONA. Bilateral ONA is most likely to be due to failure of the retinal ganglion cells to develop, consequently, the optic disc and nerve, and the retinal blood vessels are absent. Bilateral ONA is rare, and is associated with major CNS anomalies, and with other multiple, often severe congenital malformations. Bilateral ONA appears to be a distinct entity, independent from its unilateral counterpart and can be adequately diagnosed on clinical grounds.