Objective: To determine whether IgG antibodies to Chlamydia pneumoniae are associated with nonarteritic ischemic optic neuropathy (NAION).
Design: Retrospective case-control study.
Participants: The study cohort consisted of 71 consecutive patients with NAION and 71 controls matched for age and gender.
Main outcome measures: Serum immunoglobulin G (IgG) antibody titers to Chlamydia pneumoniae.
Results: Patients with NAION had significantly higher IgG antibody titers to C. pneumoniae compared with control subjects (IgG titer > or =1:128: 29 patients versus 15 controls, P = 0.017). The odds ratio for patients with an IgG titer > or =1:128 was 2.56 (95% confidence interval [CI], 1.2-5.5). Adjustment for arterial hypertension, diabetes mellitus, and myocardial infarction resulted in an odds ratio of 3.48 (95% CI, 1.3-9.6).
Conclusions: Our results suggest that elevated titers of IgG antibodies to C. pneumoniae are associated with NAION.