Primary idiopathic inflammation of the optic nerve.

A 50-year-old woman with progressive right-sided visual loss had severely reduced visual acuity in the right eye and an upper temporal visual field defect in the left eye. Extensive neuroradiologic studies disclosed an enlarged right optic nerve, and a transfrontal craniotomy. Biopsy of the right optic nerve showed perivascular lymphocytic infiltration and a few atypical astrocytes. A complete medical evaluation gave no evidence of systemic vasculitis or lymphoreticular malignancy. Oral corticosteroids were administered for two months, and no further deterioration of vision occurred. Two years later, although the right eye was blind, the visual acuity of the left eye was 6/2 (20/20), and the patient had no clinical or radiologic evidence of optic chiasm tumor.