Bleb related infections: clinical characteristics, risk factors, and outcomes in an Asian population

Zhu Li Yap,1,2 You Chuen Chin,1 Judy Yu-Fen Ku,1 Tat Keong Chan,1,2 Gillian Teh,1,2 Monisha Esther Nongpiur,2,3 Tin Aung,1,2 Shamira A Perera1–3 1Singapore National Eye Centre, Singapore; 2Singapore Eye Research Institute, Singapore; 3Duke NUS Graduate Medical School, Singapore Purpose: Comparison of the demographic, ocular, systemic and microbiological characteristics of eyes with bleb related infection (BRI) and bleb related endophthalmitis (BRE). Methods: Retrospective chart review of patients with BRI from January 1996–July 2013. Identification done via the center’s longstanding endophthalmitis audit, BRI audit and laboratory database identifying all conjunctival swabs from blebs. Blebitis was defined as anterior segment inflammation with mucopurulent material in or around the bleb, with anterior chamber cells but no hypopyon. BRE was defined by the presence of hypopyon or vitreous inflammation. Results: Twenty-nine patients with blebitis and 10 with BRE were identified. Mean age of subjects (n=39) was 68.4 (±13.3) with a preponderance of men (74.4%) and Chinese ethnicity (74.4%). BRE patients were 10.7 years older than blebitis patients (P=0.026). 28 (71.8%) subjects had primary open angle glaucoma. The presenting intraocular pressure (IOP) dropped in blebitis but almost doubled in BRE (P=0.011) compared to average preinfective IOP. Two weeks after treatment, IOPs in both groups returned to close to preinfective levels. Subjects with blebitis more often had an avascular bleb (88.0%) while those with BRE trended toward a moderately vascular bleb (50%). The distribution of causative microorganisms between the groups was similar. Conclusion: Our study indicates that risk factors are similar in both groups even though the visual outcome and clinical course, in the form of IOP findings and bleb vascularity, can diverge significantly. The decreased IOP in blebitis subjects represents objective evidence of subclinical leaks or bleb sweating. Keywords: bleb related endophthalmitis, blebitis, post-trabeculectom