Ischemic optic neuropathy decompression trial - Twenty-four-month update

Objective: To describe visual acuity outcomes of patients in the Ischemic O ptic Neuropathy Decompression Trial (IONDT) after 24 months of follow-up. Design: The IONDT is a single-masked, multicenter, randomized clinical tria l. Settings: Patients were evaluated and followed up at 25 clinical centers lo cated throughout the United States. Data were sent to and analyzed at a cen tral coordinating center. Patients: Two hundred fifty-eight patients SO years or older with nonarteri tic anterior ischemic optic neuropathy and visual acuity of 20/64 or worse, but better than no light perception, were randomized to either a careful f ollow-up group (n=131) or an optic nerve decompression surgery (ONDS) group (n=127). Of these, 174 continued participation for at least 24 months, 89 in the careful follow-up group and 85 in the ONDS group. Methods: Randomized patients underwent a standard visual acuity examination at 3, 6, 12, 18, and 24 months of follow-up. The primary outcome was a cha nge of 3 lines or more of visual acuity, defined as a difference of 0.3 in logMAR scores, between baseline and 6 months of followup. A secondary outco me was mean change in visual acuity (in logMAR units) at 3, 6, 12, 18, and 24 months following baseline. These changes were estimated using available data from all randomized patients for whom we had data. Results: Of the 258 patients randomized, 143 (55.4%) were male, and 169 (65 .5%) were 65 years or older. Mean visual acuity was statistically significa ntly improved from baseline value at all study visits and for both treatmen t groups, although visual acuity declined gradually in both groups after th e 3-month visit. There were no significant differences between careful foll ow-up and ONDS in mean change in vision from the baseline and any follow-up time point. At 24 months of follow-up, 31.0% of patients in the careful fo llow-up group and 29.4% of patients in the ONDS group experienced an increa se of 3 or more lines of vision compared with baseline acuity; 21.8% of pat ients in the careful follow-up group and 20.0% of patients in the ONDS grou p experienced a decrease of 3 or more lines. In patients who could read at least 1 letter on the Lighthouse chart, there wets a gradual decline in mea n visual acuity noted over time for both treatment groups, although acuity remained significantly better than at baseline. Conclusion: Analysis of visual acuity data from patients enrolled in the IO NDT at 24 months of follow-up confirms that there is no benefit of ONDS com pared with careful follow-up in patients with nonarteritic anterior ischemi c optic neuropathy.