Optic atrophy in acute intermittent porphyria.

A 24-year-old woman developed bilateral blindness after recovery from coma secondary to acute intermittent porphyria. Gradual return of vision in the right eye with a permanent unilateral visual field defect and optic atrophy followed. We believe the pathophysiologic mechanism was spasm of the vessels supplying the optic disk leading to ischemia and infarction of the optic nerve.