Risk factors for development of post-trabeculectomy endophthalmitis

Although adjunctive use of antiproliferative agents improves the success rate of glaucoma filtration surgery it profoundly alters the morphology of the filtering bleb. In view of these structural changes, which have been suggested to predispose to bleb infection, the relative importance of potential risk factors in the development of post-trabeculectomy endophthalmitis was investigated.

A case-control study was performed on patients with post-trabeculectomy endophthalmitis presenting to a single academic centre over a 6 1/2 year period. Cases were diagnosed by the combination of vitreous and aqueous inflammation occurring 4 or more weeks postoperatively with control patients chosen by selecting the three patients undergoing trabeculectomy immediately following each index case.

Analysis of these data, derived from 23 cases and 69 controls, demonstrated that an episode of blebitis and the presence of diabetes mellitus were statistically significantly associated with subsequent endophthalmitis (odds ratios (OR) 11.8, 95% CI: 2.21-88.31, p = 0.003 and OR 4.51, 95 % CI 1.02-20.29, p = 0.04 respectively). The data also suggest an association exists between antiproliferative use and endophthalmitis (OR 3.3, 95% CI 0.95-15.19, p = 0.07) as the time interval between filtration surgery and development of endophthalmitis was significantly shorter in patients treated with antiproliferative agents (p = 0.001).

These results provide strong evidence of an increased risk of late endophthalmitis in patients who have diabetes mellitus or have had an episode of blebitis and suggest antiproliferative agents may also have an important role.