Characteristics of patients with nonarteritic anterior ischemic optic neuropathy eligible for the ischemic optic neuropathy decompression trial

Objective: To describe the baseline clinical characteristics of patients in the Ischemic Optic Neuropathy Decompression Trial (IONDT). Design: The IONDT is a single-masked, multicenter, randomized clinical trial. Settings: Twenty-five US clinical centers. Patients: Eligibility criteria for randomization to either optic nerve sheath decompression surgery or careful follow-up included a diagnosis of acute unilateral non-arteritic anterior ischemic optic neuropathy (NAION), a visual acuity of 20/64 or worse and better than no light perception, and an age of 50 years or older. Patients who were eligible except for having visual acuity better than 20/64 were not randomized, but were followed up. Methods: Each patient underwent a standardized history and examination by certified study personnel within 14 days of the onset of symptoms. Masked personnel performed outcome measurements. Results: Of 420 patients with NAION, 258 were randomized, and 162 were not randomized and are being followed up. Sixty-two percent of the patients were men and 95% were white. The mean±SD age at onset was 66.0±8.7 years. Hypertension was reported in 47% of the patients in the IONDT, and 24% of the patients had diabetes mellitus. Forty-two percent of the patients recalled the onset of visual symptoms to be within 2 hours of awakening. Initial visual acuities in the study eye ranged from 20/20 or better to light perception, with 49% of the patients seeing better than 20/64 and 34% of the patients seeing 20/200 or worse. The mean Westergren sedimentation rate was 18.4 mm/h, with 9% of the patients having a rate greater than 40 mm/h. The nonrandomized patients (visual acuity better than 20/64) were younger, 72% were male, and they had a lower prevalence of hypertension and diabetes mellitus. Conclusion: Although our baseline findings are derived from a selected population of patients with NAION who were eligible for the IONDT, they provide the first description of NAION from a large prospective study that used a standard definition of NAION and only included patients who were identified within 2 weeks of the onset of symptoms.