Visual loss as a complication of nonophthalmologic surgery: a review of the literature.

Decreased visual acuity and loss of visual ability are devastating anesthetic and surgical complications. The incidence is greater in patients with preexisting hypertension, diabetes, sickle cell anemia, renal failure, gastrointestinal ulcer, narrow-angle glaucoma, vascular occlusive disease, cardiac disease, arteriosclerosis, polycythemia vera, and collagen vascular disorders. Precipitating factors for ischemic optic neuropathy include prolonged hypotension, anemia, surgery, trauma, gastrointestinal bleeding, hemorrhage, shock, prone position, direct pressure on the globe, and long operative times. Prone and Trendelenburg positions can lead to visual loss related to decreased venous return from the head. Visual impairment may result from increased intracranial pressure, which contributes to undue pressure on the optic nerve. The prone position increases the risk of direct compression injury to the orbit and corneal abrasion. Astute attention to positioning is imperative, especially with the prone position. At-risk patients should receive transfusion once the calculated allowable blood loss has been surpassed. Unacceptable hemoglobin and hematocrit values should be corrected preoperatively and levels monitored during the case to avoid intraoperative anemia in at-risk patients. The blood pressure of patients with predisposing diseases should be kept within normal limits. To avoid this devastating complication, it is imperative that anesthesia providers understand contributing factors and prevention strategies.