Objective: To determine the influence of certain potential risk factors on the occurrence of nonarteritic anterior ischemic optic neuropathy.
Design: Case-control using 2 independent control groups, one involving a geographically defined population and the other involving patients who underwent a routine comprehensive medical evaluation.
Setting: Multispecialty clinic in a rural setting providing primary, secondary, and tertiary care for residents of central and northern Wisconsin and the Upper Peninsula of Michigan.
Patients: Fifty-one patients older than 45 years with first ever acute nonarteritic anterior ischemic optic neuropathy.
Main outcome measures: Potential risk factors defined using standardized definitions abstracted from the medical records, including diabetes, hypertension, hypercholesterolemia, coronary artery disease, tobacco use, chronic obstructive pulmonary disease, body mass index, hematocrit, and white blood cell count.
Methods: Conditional logistic regression analyses, first using a univariate analysis and then employing a multivariate analysis using a forward selection process.
Results: The geographically defined case-control multivariate analysis revealed that diabetes (odds ratio = 2.7, 95% confidence interval = 1.2-6.3, P = .02) and body mass index (odds ratio = 1.07, 95% confidence interval = 1.00-1.14, P = .08) were associated with case status. The comprehensive case-control multivariate analysis revealed that only diabetes (odds ratio = 5.0, 95% confidence interval = 1.4-17.3, P = .01) was a significant risk factor. The attributable risk estimation for diabetes was 0.21 and 0.27 for the geographically defined and comprehensive controls, respectively.
Conclusions: Diabetes seems to be a major risk factor for the development of nonarteritic anterior ischemic optic neuropathy. The low attributable risk estimation suggests that factors other than diabetes are important in the development of nonarteritic anterior ischemic optic neuropathy or in predisposing individuals to it.