Bilateral Optic Nerve Cryptococcosis in Sudden Blindness in Patients with Acquired Immune Deficiency Syndrome

Abstract

A neuroanatomic study was undertaken to search for the cause of sudden, simultaneously bilateral blindness in a patient with acquired immune deficiency syndrome who had cryptococcal meningitis. Careful gross examination was performed, and microscopic sections were cut at 50- to 100-microns intervals of the entire visual pathway. Focal cryptococcosis destroyed segments of the right intracanalicular optic nerve and the left intraorbital optic nerve adjacent to the optic canal. The meninges were heavily infiltrated by Cryptococcus organisms around the optic tracts, optic nerves, and optic chiasm; however, only a few scattered cryptococcal organisms were found in the periphery of the chiasm contiguous with heavy meningeal infection. Blood vessels supplying the chiasm appeared normal. Generalized cerebral edema and focal vacuolization of periventricular white matter were evident. The authors believe that sudden, simultaneously bilateral visual loss in this patient was caused by focal but fulminant necrosis of both optic nerves. However, the presence of cryptococcal organisms throughout the basal meninges and in the sheaths of both optic nerves suggests that cryptococcosis may produce visual loss by damaging multiple areas of the anterior visual pathway.