Chronic asymptomatic ischemic optic neuropathy. A report of two cases in adults with diabetes mellitus.

Two adult diabetic patients with chronic asymptomatic optic neuropathy attributed to an ischemic etiology are reported. In one case the typical syndrome of ischemic optic neuropathy occurred in one eye, while the fellow eye had asymptomatic hyperemic optic disc edema that persisted for 6 months without optic atrophy. A minor visual field defect initially detected in that eye resolved spontaneously in 1 month. In the second case, a recent onset, middle-aged diabetic developed bilateral optic neuropathy and optic disc edema that persisted for 12 months, with minimal signs of visual dysfunction. Axoplasmic transport blockage from low-grade ischemia to the optic nerve may cause acute or chronic optic disc edema with minimal or no visual symptoms.