Posteriorc ischemic optic neuropathy (PION) is an uncommon cause of perioperative visual loss which is usually devastating. This thorough review summarizes most cases published in the English literature. Perioperative PION has been most frequently reported after spinal surgery and radical neck dissection. The visual loss typically presents immediately after recovery from anesthesia, although it may be delayed by several days. Visual loss is often bilateral and profound with count fingers vision or worse. The examination findings are consistent with an optic neuropathy; however, the funduscopic examination is initially normal. The cause is unknown, although patient-specific susceptibility to perioperative hemodynamic derangements is likely. No treatment has proven to be effective. The prognosis for visual recovery is generally poor. — Valérie Biousse.