Unilateral blindness: etiology


Postoperative blindness is a devastating and fortunately rare complication of general anesthesia. The incidence of postoperative blindness is low (Ref. 1). In one retrospective study, only one out of 60965 patients suffered permanent loss of vision. (Ref. 2)

Post-operative visual loss typically occurs as an ischemic sequelae of external compression of the globe, hypotension, anemia or embolism (Miller 2010). The causes of post-operative unilateral blindness and their possible mechanisms include :

1. Ischemic optic neuritis (ION): anterior ION usually occurs after cardiac surgery and posterior ION typically occurs after spine surgery. This is the most common cause of perioperative vision loss. (Ref. 2). It can be unilateral although most cases are bilateral. ION results from hypoperfusion or decreased oxygen delivery to the optic nerve either in the anterior portion (AION) or the posterior portion (PION). Clinical findings of ION include painless visual loss, and impaired color vision. Fundoscopic exam findings include optic disc edema in AION, however in PION the optic disc may appear normal initially. Visual defects tend to be altitudinal, or loss of vision occurs with respect to the horizontal meridian. (Miller 2010)

2. Central Retinal Artery Occlusion (CRAO): may occur as a result of external compression on the eye causing raised intraocular pressure that blocks blood flow through the central retinal artery, retrobulbar hemorrhage from vasuclar injury or from an emboism. Clinical findings include “painless blindness,” “cherry red macula” and narrowed retinal arteries on fundoscopic exam. Causes of CRAO include 1) raised intraocular pressure, 2) embolism, 3) decreased venous outflow. (Miller 2010)

3. Branch retinal artery occlusion (BRAO): occurs most commonly from an embolism in one branch of the central retinal artery. BRAO presents as loss of vision in a defined distribution of the arterial branch affected. Clinical presentation may be silent if the vision loss is peripheral. Embolism may be identified and characterized by fundoscopic examination. (Miller 2010)

4. Acute angle glaucoma: results in raised intraocular pressure from blockade of the aqueous humor outflow tract from obliteration of the space between the iris and lens. Clinical findings include a painful and red globe, blurry vision, headache, nausea and vomiting. (Miller 2010) Although a cause of unilateral blindness, case reports have described bilateral acute angle closure glaucoma after spine surgery. (Ref. 3, Ref. 4)


Keyword history




  1. Nancy J Newman Perioperative visual loss after nonocular surgeries. Am. J. Ophthalmol.: 2008, 145(4);604-610
  2. Roth, R A Thisted, J P Erickson, S Black, B D Schreider Eye injuries after nonocular surgery. A study of 60,965 anesthetics from 1988 to 1992. Anesthesiology: 1996, 85(5);1020-7
  3. Michael S Singer, Sarwat Salim Bilateral acute angle-closure glaucoma as a complication of facedown spine surgery. Spine J: 2010, 10(9);e7-9
  4. Etienne Gayat, Eric Gabison, Jean-Michel Devys Case report: bilateral angle closure glaucoma after general anesthesia. Anesth. Analg.: 2011, 112(1);126-8