Isolated optic nerve hypoplasia

Definition

A rare developmental defect during embryogenesis characterized by underdevelopment of the optic nerve with a subnormal number of optic nerve axons. The condition may be unilateral or bilateral and can occur as an isolated defect or accompany other ocular or cerebral abnormalities. Funduscopic examination reveals a small optic disc, often associated with the ''double-ring'' sign, a ring of hypo- or hyperpigmentation surrounding the disc. Clinically, vision may be severely impaired or remain unaffected.