OPTIC-NERVE DECOMPRESSION SURGERY FOR NONARTERITIC ANTERIOR ISCHEMIC OPTIC NEUROPATHY (NAION) IS NOT EFFECTIVE AND MAY BE HARMFUL

Objective.-To assess the safety and efficacy of optic nerve decompress ion surgery compared with careful follow-up alone in patients with non arteritic anterior ischemic optic neuropathy (NAION). Design.-The Isch emic Optic Neuropathy Decompression Trial (IONDT) is a randomized, sin gle-masked, multicenter trial. Setting.-Twenty-five US clinical center s. Participants.-The IONDT ceased recruitment on October 20, 1994, on the recommendation of its Data and Safety Monitoring Committee. The pr eliminary results presented herein are based on data as of September 8 , 1994, from 244 patients with NAION and visual acuity of 20/64 or wor se. One hundred twenty-five patients had been randomized to careful fo llow-up, and 119 had been randomized to surgery, with 91 and 95, respe ctively, having completed 6 months of follow-up. Intervention.-Patient s in the surgery group received optic nerve decompression surgery and follow-up ophthalmologic examinations; those in the careful follow-up group received ophthalmologic examinations at the same times as the su rgery group. Main Outcome Measures.-Gain or loss of three or more line s of visual acuity on the New York Lighthouse chart at 6 months after randomization, as measured by a technician masked to treatment assignm ent. Results.-Patients assigned to surgery did no better when compared with patients assigned to careful follow-up regarding improved visual acuity of three or more lines at 6 months: 32.6% of the surgery group improved compared with 42.7% of the careful follow-up group. The odds ratio (OR) for three or more lines better, adjusted for baseline visu al acuity and diabetes, was 0.74 (95% confidence interval [Cl], 0.39 t o 1.38). Patients receiving surgery had a significantly greater risk o f losing three or more lines of vision at 6 months: 23.9% in the surge ry group worsened compared with 12.4% in the careful follow-up group. The 6-month adjusted OR for three or more lines worse was 1.96 (95% Cl , 0.87 to 4.41). No difference in treatment effect was observed betwee n patients with progressive NAION and all others. Conclusion.-Results from the IONDT indicate that optic nerve decompression surgery for NAI ON is not effective, may be harmful, and should be abandoned. The spon taneous improvement rate is better than previously reported.