Le Fort I osteotomy is used as a surgical procedure for correction of maxillofacial deformities. The common complications of this procedure are hemorrhage and infection, with incidence of 6% to 9%. Blindness associated with Le Fort I osteotomy was reported in 8 patients. An 18-year-old female complained of loss of sight in the left eye after recovery from hypotensive general anesthesia. The visual field of the left eye was dark and only perceived some movement. She presented with motor dysfunction and regressive behavior 2 weeks later as a result of hypoxia of bilateral basal ganglia. Two months later, her visual acuity recovered gradually and regressive behavior improved. Carotid angiography showed congenital hypoplasia of the left internal carotid artery. We suspected that hypoplasia could cause hypoxia of the central nervous system.