Intraorbital optic nerve signal hyperintensity on magnetic resonance imaging sequences in perioperative hypotensive ischemic optic neuropathy.

A 61-year-old man experienced severe bilateral posterior ischemic optic neuropathy after cardiac bypass surgery. Routine magnetic resonance imaging sequences were normal, but diffusion-weighted and fluid-attenuated inversion recovery (FLAIR) sequences showed abnormal hyperintensity within both intra-orbital optic nerves. This imaging abnormality has not been previously reported in this setting.