Incidence of nonarteritic anterior ischemic optic neuropathy

PURPOSE: Nonarteritic anterior ischemic optic neuropathy is the most common acute optic nerve disease of adults over age 50 years. This study determined the incidence of acute nonarteritic anterior ischemic optic neuropathy in the circumscribed population of Olmsted County, Minnesota. METHODS: This was a retrospective study of the incidence of acute nonarteritic anterior ischemic optic neuropathy between 1981 and 1990. The Rochester Epidemiology Project medical records linkage system facilitates identification of the medical records of virtually all Olmsted County residents with a given diagnosis. All cases of acute nonarteritic anterior ischemic optic neuropathy that fulfilled certain inclusion and exclusion criteria were identified. RESULTS: Twenty-two cases in 21 patients (11 men and 10 women) were recorded. The crude annual incidence rate was 10.3 per 100,000 individuals (95% confidence interval [CI] = 5.1 to 18.4). When adjusted to the age and sex distribution of the 1990 United States white population, the incidence rate was 10.2 per 100,000 (95% CI = 6.5 to 15.6). At diagnosis, the median age was 72 years, mean visual acuity was 20/200 in the affected eye, and the most common visual field defect was an altitudinal deficit (10 cases). CONCLUSIONS: Although results of this small study should be interpreted cautiously, extrapolation of our findings to the United States white population indicates that nearly 5,700 new cases of acute nonarteritic anterior ischemic optic neuropathy may be expected to occur each year in this group.