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 nonarteritic 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.