Needling for encapsulated trabeculectomy filtering blebs

Trabeculectomy is an eye operation aimed at reducing intraocular pressure in people with glaucoma. A bleb usually forms at the site of operation, indicating aqueous drainage from the eyes. Trabeculectomy blebs can become encapsulated leading to poor drainage and high intraocular pressure. Some ophthalmologists needle encapsulated blebs in order to re-establish drainage and lower intraocular pressure. However, needling is invasive and can potentially be associated with higher risks of complications, such as anterior chamber collapse, infections, and cataract. This review included one trial conducted in Brazil which randomised 25 eyes. The trial compared needling using a 27-gauge needle to medical treatment with aqueous suppressants and digital massage. Outcome measures in the trial were mean intraocular pressure and successful intraocular pressure control (defined arbitrarily as IOP less than 20 mmHg). This review found no conclusive evidence that needling of encapsulated blebs results in better intra-ocular pressure control than antiglaucoma medication.

Authors' conclusions: 

Evidence from one small trial suggests that needling of encapsulated trabeculectomy blebs is not better than medical treatment in reducing intraocular pressure.

Read the full abstract...

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.


The objective of this review was to assess the effects of needling encapsulated blebs on intraocular pressure.

Search strategy: 

We searched 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) (, ( and the WHO International Clinical Trials Registry Platform (ICTRP) ( We did not use any date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 14 February 2012.

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 review authors 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 mmHg, standard deviation 5.9) than the medical group (19.45 mmHg, 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.

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