Risk factors for glaucoma filtering bleb infections

Objective: To determine risk factors for bleb-related ocular infection after glaucoma filtering surgery. Methods: A case-control study comparing all consecutive cases of glaucoma filtering bleb-related infections (55 eyes of 55 patients) with matched control eyes between January 1, 1990, and June 30, 1998, was performed. Bleb-related infection was classified as blebitis when a mucopurulent infiltrate was identified within the bleb and associated Kith mild to moderate anterior segment inflammation. Eyes with endophthalmitis had hypopyon, cells in the anterior vitreous cavity, or a positive vitreous biopsy sampling result. A control was selected for each case based on matching of the surgeon, date and type of glaucoma surgery, and type of antifibrotic agent used. Multivariate, matched, case-control logistic regression analysis was performed using age, race, sex, diagnosis, number of previous incisional operations, filtering bleb location, and presence of bleb leak to determine which variables were associated with bleb-related infection. Results: The odds of an eye with a bleb-related infection being seen with a concomitant late-onset bleb leak are 25.8 times the odds of a noninfected eye having a late-onset bleb leak at any time in the postoperative period (P<.001; 95% confidence interval, 2.3-294.1). Other risk factors for bleb-related infection included younger age (P = .05), black race (P = .03), diagnosis of primary open-angle glaucoma (P = .03), and inferior location of the filtering bleb (P = .04). Conclusions: Late-onset bleb leakage is a significant risk factor for bleb-related infection. The risk of infection may warrant closure of late-onset bleb leaks in selected eyes.