The purpose of this advisory is to enhance awareness of permanent impairment or total loss of sight associated with a spine procedure during which general anesthesia is administered and to reduce its frequency.  The conditions addressed in this advisory are posterior ischemic optic neuropathy (PION), anterior ischemic optic neuropathy (AION) and central retinal artery occlusion (CRAO).  These guidelines will be published in Anesthesiology in 2006.