Optic nerve hypoplasia: changing perspectives.

Optic nerve hypoplasia, having once been regarded as exceedingly rare, is now regarded as one of the major causes of visual loss in infancy. Recognition of subtle forms and segmental forms of optic nerve hypoplasia are important in explaining the evaluation of subnormal vision, and have an added significance in the recognised associations of central nervous system anomalies including abnormalities of the endocrine system. These changing clinical perspectives are reviewed, together with a discussion of the pathogenesis of optic nerve hypoplasia in the light of cell death and nerve fibre degeneration seen in normal development of the neural visual system.