Perioperative Visual Loss

Abstract

Visual loss after anesthesia and surgery is an unexpected and a devastating complication. Symptoms and signs of eye injury associated with visual loss are not generally familiar to most anesthesiologists. The incidence of visual loss postoperatively has been estimated at 0.056%– 1.3%. Cases can be divided into retinal ischemia, Ischemic Optic Neuropathy (ION), cortical blindness, acute glaucoma and corneal abrasions. Blood supply to the retina and the optic nerve depends on the intraocular perfusion pressure. This perfusion pressure is defined as the difference between the mean arterial pressure and the intraocular pressure (IOP). High IOP impairs the blood supply, leading to a loss of optic nerve function. A decrease in mean arterial blood pressure diminishes ocular perfusion pressure (the difference between mean arterial and retinal venous pressure). Increases in IOP decrease retinal and choroidal blood flow. Changes in hematocrit may alter ocular blood flow. Hemodilution increased retinal blood flow by 71% and preserved retinal oxygen delivery while producing a significant 19% decrease in choroidal blood flow.