A 70-year-old man underwent coronary artery bypass graft complicated postoperatively by visual loss. The diagnosis was nonarteritic anterior ischemic optic neuropathy. Possible predisposing factors in this patient were hypotension, anemia, a "disk at risk," and internal carotid artery stenosis. In the postoperative setting, the erythrocyte sedimentation rate may be elevated, as it was in this case and does not by itself suggest a diagnosis of giant cell arteritis. (C) 1998 by Elsevier Science Inc. All rights reserved.).