Risk factors for late-onset infection following glaucoma filtration surgery.

OBJECTIVE To determine the risk factors for late-onset infection following glaucoma filtration surgery. METHODS We performed a case-control study comparing 131 cases of late-onset infection collected from 27 surgeons at 10 centers with 500 controls matched for date of surgery and surgeon. The criterion for the presence of infection was severe anterior chamber reaction occurring later than 4 weeks after surgery. An opaque bleb and positive culture results were not required for diagnosis. Risk factors were identified by univariate and multivariate logistic regression analyses. RESULTS Some of the risk factors that were statistically significant in the multivariate model after adjusting for age, race, and sex were (1) performance of a full-thickness rather than a guarded procedure (risk ratio [RR], 13.1; 95% confidence interval [CI], 2.12-80.9), (2) filtration surgery performed without concurrent cataract surgery (RR, 2.25; 95% CI, 1.24-4.08), (3) use of mitomycin (RR, 2.48; 95% CI, 1.06-5.83), (4) intermittent use of antibiotics after surgery (RR, 2.10; 95% CI, 1.09-4.02), and (5) continuous use of antibiotics after surgery (RR, 5.94; 95% CI, 2.09-16.9). CONCLUSIONS Eyes undergoing full-thickness procedures or filtration surgery without cataract extraction are at increased risk for late infection. Intraoperative mitomycin and episodic or continuous antibiotic use after the postoperative period are associated with an increased risk of infection.