Needling for encapsulated trabeculectomy filtering blebs

Methodological quality of the review: Medium confidence

Author: Feyi-Waboso A, Ejere HOD

Geographical coverage: Brazil

Sector: Glaucoma

Sub-sector: Intra-ocular pressure

Equity focus: None specified

Review type: Effectiveness review

Quantitative synthesis method: Narrative synthesis

Qualitative synthesis method: Not applicable

Background: Encapsulation of a filtering bleb following trabeculectomy (Trab) may lead to elevation of intra-ocular pressure (IOP), 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 IOP.

Objectives: To assess the effects of needling encapsulated blebs on intra-ocular pressure.

Main findings: One trial conducted in Brazil, which randomised 25 eyes to either needling or medical treatment, met the inclusion criteria. At one-day post-treatment, mean IOP was lower in the needling group (16.28 mm Hg, SD 5.9) than the medical group (19.45 mm Hg, SD 3.75). The difference was not statistically significant.

At all other follow-up points, mean IOP 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.

Authors noted that evidence from one small trial suggests that needling of encapsulated Trab blebs is not better than medical treatment in reducing IOP. There is a need for more randomised controlled trials (RCTs) to validate the findings of this single trial and provide more information on the role and safety of needling in the management of encapsulated blebs. The adjuvant use of anti-metabolite with needling requires examination. The role of digital massage in bleb re-modelling also needs further evaluation.

Methodology: The following databases were searched for relevant studies: CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 1), MEDLINE (January 1950 to February 2012), EMBASE (January 1980 to February 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to February 2012), the metaRegister of Controlled Trials (mRCT), ClinicalTrials and the WHO International Clinical Trials Registry Platform (ICTRP). Reference lists of included studies were also reviewed for further studies. No restrictions were applied.

Inclusion criteria consisted of: randomised and quasi-randomised controlled trials; participants in trials were people with encapsulated Trab blebs; and trials in which bleb needling was compared to any form of anti-glaucoma medication. The primary outcome measure of the review was mean IOP measured in millimetres of mercury at day one, one week, one month and at the last available follow-up.

Data was independently extracted by two reviewers using a form developed by the Cochrane Eyes and Vision Group. Assessment of risk of bias assessed the following criteria: allocation concealment, completeness of follow-up and intention-to-treat analysis.

Applicability/external validity: Authors note that there is a need for more RCTs to validate the findings of this single trial and provide more information on the role and safety of needling in the management of encapsulated blebs.

Geographic focus: This review focuses on all countries; only one study was included.

Summary of quality assessment: Overall, there is medium confidence in the conclusions about the effects of this study, as minor limitations were identified. Although authors did not contact authors/experts for further studies as part of the search strategies, a thorough search of the literature was conducted on databases and references of included studies were reviewed to ensure that all relevant studies were identified, avoiding restriction bias. Authors used appropriate methods to select studies for inclusion and to extract data and assess the risk of bias of the included study. Authors used a narrative synthesis, which seemed appropriate as only one study was included.