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Factors predicting the success of trabeculectomy bleb enhancement with needling
  1. Jonathan Y-X L Than1,2,
  2. Toby S Al-Mugheiry1,
  3. Jesse Gale3,4,
  4. Keith R Martin1,4
  1. 1Cambridge NIHR Biomedical Research Centre, University of Cambridge, Cambridge, UK
  2. 2Department of Ophthalmology, North Middlesex University Hospital NHS Trust, London, UK
  3. 3Department of Surgery & Anaesthesia, University of Otago Wellington, Wellington, New Zealand
  4. 4Department of Ophthalmology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
  1. Correspondence to Dr Jesse Gale, Department of Surgery and Anaesthesia, University of Otago Wellington, Wellington 6242, New Zealand; jesse.gale{at}


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.

  • needling
  • intraocular pressure
  • medications
  • glaucoma
  • trabeculectomy
  • glaucoma drainage implants
  • surgery

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  • Contributors JYXLT and TSAl-M contributed equally to this paper and should thus be regarded as joint first authors. JYXLT and TSAl-M carried out data acquisition and analysis, drafted the manuscript and approved final draft submission. JG was involved in design of the study, carried out data acquisition, drafting and critical revision of the manuscript and approved final draft submission. KRM conceived and designed the study, helped draft and critically revise the manuscript and approved final draft submission. All authors agreed to be accountable for all aspects of the work submitted.

  • Competing interests None declared.

  • Ethics approval Ethical approval for the study was sought from the clinical audit department at Addenbrooke’s Hospital, based on the retrospective design and adherence to privacy standards.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement Full dataset and analysis of all cases presented within the manuscript is available upon request through contact with the corresponding author of the submission via email.

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