Background Bleb needling is widely used to restore flow and lower intraocular pressure (IOP) in a failing trabeculectomy. We aimed to measure the safety and efficacy of needling in a large cohort and identify factors that were associated with success and failure.

Methods This retrospective audit included all patients who underwent needling at Addenbrooke’s Hospital, Cambridge over a 10-year period. Data were available on 91 patients (98% of patients identified), including 191 needlings on 96 eyes. Success was defined as IOP below 21 mm Hg or 16 mm Hg or 13 mm Hg consistently, without reoperation or glaucoma medication. Risk factors for failure were assessed by Cox proportional hazard regression and Kaplan-Meier curves.

Results Success defined as IOP <16 mm Hg was 66.6% at 12 months and 53% at 3 years and success defined as IOP <21 mm Hg was 77.1% at 12 months and 73.1% at 3 years. Failure after needling was most common in the first 6 months. Factors that predicted failure were flat or fibrotic blebs (non-functional) and no longer injected, while success was predicted by achieving a low IOP immediately after needling. No significant complications were identified.

Conclusion Needling was most successful soon after trabeculectomy, but resuscitation of a long-failed trabeculectomy had lower likelihood of success. The safety and efficacy compare favourably with alternative treatment approaches.