RT Book, Section A1 Effron, David A1 Forcier, Beverly C. A1 Wyszynski, Richard E. A2 Knoop, Kevin J. A2 Stack, Lawrence B. A2 Storrow, Alan B. A2 Thurman, R. Jason SR Print(0) ID 1181039706 T1 Anterior Ischemic Optic Neuropathy T2 The Atlas of Emergency Medicine, 5e YR 2021 FD 2021 PB McGraw-Hill PP New York, NY SN 9781260134940 LK accessemergencymedicine.mhmedical.com/content.aspx?aid=1181039706 RD 2024/10/06 AB Anterior ischemic optic neuropathy (AION) presents with a sudden loss of visual field (often altitudinal), usually involving fixation, in an older individual. The loss is usually stable after onset, with no improvement, and only occasionally, progressive over several days to weeks. In contrast to the hyperemic appearance that usually accompanies optic nerve head edema, pale disk swelling is present involving a sector or the full disk, sometimes with accompanying flame hemorrhages. The cup-to-disk ratio is typically small (0.1-0.2) bilaterally.