title: Surgery for nonarteritic anterior ischemic optic neuropathy.
abstract: BACKGROUND
  Nonarteritic ischemic optic neuropathy (NAION) is characterized by sudden and painless loss of vision in the eye, accompanied by pallid swelling of the optic disc. Its etiology is unknown and no medical therapy has been proven effective in treating this condition. Optic nerve decompression surgery, a proposed treatment for NAION, involves making two or more slits or a window in the tissue surrounding the optic nerve, thereby allowing cerebrospinal fluid to escape, and theoretically reducing the pressure surrounding the optic nerve.
  
  
  OBJECTIVE
  The objective of this review was to assess the safety and efficacy of surgery compared with other treatment or no treatment in people with nonarteritic ischemic optic neuropathy.
  
  
  METHODS
  We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2011, Issue 11), MEDLINE (January 1950 to November 2011), EMBASE (January 1980 to November 2011), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (http://clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 19 November 2011.
  
  
  METHODS
  All randomized trials of surgical treatment of NAION were eligible for inclusion in this review.
  
  
  METHODS
  We obtained full copies of all potentially relevant articles. One author extracted data which was verified by another author. No data synthesis was required.
  
  
  RESULTS
  The one included trial randomized 258 participants and was stopped early for futility. At the time of the 24-month report the follow-up rate was 95.3% for six months and 67.4% for 24 months (174 participants; 89 careful follow up and 85 surgery). There was no evidence of a benefit of surgery on visual acuity. Measurements of visual acuity and visual fields were performed by a technician masked to the treatment received. At six months 32.0% of the surgery group had improved visual acuity by three or more lines compared with 42.6% of the careful follow up group (unadjusted relative risk (RR) 0.75, 95% confidence interval (CI) 0.54 to 1.04). At 24 months 29.4% of the surgery group had improved compared with 31.0% of the careful follow up group (unadjusted RR 0.95, 95% CI 0.60 to 1.49). Participants who underwent surgery had a greater risk of losing three or more lines of vision, although the increased risk was not statistically significant. At six months 18.9% in the surgery group had worsened compared with 14.8% in the careful follow up group (RR 1.28; 95% CI 0.73 to 2.24). At 24 months 20.0% in the surgery group had worsened compared with 21.8% in the careful follow up group (RR 0.92; 95% CI 0.51 to 1.64). Participants who received surgery experienced both intraoperative and postoperative adverse events, including central retinal artery occlusion during surgery and light perception vision at six months (one participant); and immediate loss of light perception following surgery and loss of vision that persisted to the 12-month visit (two participants). In the careful follow-up group, two participants had no light perception at the six-month follow-up visit; one of these had improved to light perception at 12 months. Pain was the most common adverse event in the surgery group (17% in surgery group versus 3% in the careful follow-up group at one week). Diplopia (double-vision) was the next most common complication (8% in the surgery group versus 1% in the careful follow-up group at one week); at three months there was no statistically significant difference in proportion of participants with diplopia between the two groups.
  
  
  CONCLUSIONS
  Results from the single trial indicate no evidence of a beneficial effect of optic nerve decompression surgery for NAION. Future research should focus on increasing our understanding of the etiology and prognosis of NAION. New treatment options should be examined in the context of randomized clinical trials.
authors.affiliation: Center for Clinical Trials and US Cochrane Center, Johns Hopkins University, Bloomberg School ofPublic Health, 615 North Wolfe Street, Mail Rm W5010, Baltimore, MD, 21205, USA. kdickers@jhsph.edu.
authors.forename: Kay
authors.initials: K
authors.lastname: Dickersin
authors.forename: Eric
authors.initials: E
authors.lastname: Manheimer
authors.forename: Tianjing
authors.initials: T
authors.lastname: Li
mesh_terms: D006801:Humans; D018917:Optic Neuropathy, Ischemic / Q000601:surgery*; D011183:Postoperative Complications; D016032:Randomized Controlled Trials as Topic; D014792:Visual Acuity