Needling for encapsulated trabeculectomy filtering blebs

Abstract

BACKGROUND: Encapsulation of a filtering bleb following trabeculectomy may lead to elevation of intraocular pressure, prompting further medical or surgical intervention. It has been suggested that needling of an encapsulated bleb may be effective in re-establishing drainage and lowering intraocular pressure. OBJECTIVES: The objective of this review is to assess the effects of needling encapsulated blebs on intraocular pressure. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials - CENTRAL (which contains the Cochrane Eyes and Vision Group trials register) on The Cochrane Library (Issue 2 2003), MEDLINE (1966 to March 2003), EMBASE (1980 to May 2003) and LILACS (Latin American and Caribbean Health Sciences ) (June 2003). There were no language or date restrictions in the searches. SELECTION CRITERIA: We included randomised and quasi-randomised in which bleb needling was compared with any form of antiglaucoma medication in people with encapsulated trabeculectomy blebs. The primary outcome was mean intraocular pressure measured in millimetres of mercury at day one, one week, one month and at last available follow-up. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality and extracted data. Study authors were contacted for additional information. MAIN RESULTS: One trial, which randomised 25 eyes to either needling or medical treatment, met the inclusion criteria. At one day post-treatment, mean intraocular pressure was lower in the needling group (16.28 mm Hg, standard deviation 5.9) than the medical group (19.45 mm Hg, standard deviation 3.75). The difference was not statistically significant. At all other follow-up points, mean intraocular pressure was consistently higher in the needling group than the medical group, although the differences were not statistically significant. However, only one needled bleb remained successful at the end of follow-up compared to 10 out of the 11 blebs managed conservatively. This difference was statistically highly significant. REVIEWERS' CONCLUSIONS: Evidence from one small trial suggests that needling of encapsulated trabeculectomy blebs is not better than medical treatment in reducing intraocular pressure.