title: Pre-operative intraocular pressure does not influence outcome of trabeculectomy surgery: a retrospective cohort study.
abstract: BACKGROUND
  To investigate whether pre-operative intraocular pressure (IOP) predicts outcome of trabeculectomy surgery in patients with primary open angle glaucoma over a 3-year period of follow-up.
  
  
  METHODS
  Retrospective cohort study, of a total of 61 patients (80 procedures) who had undergone trabeculectomy surgery after failed medical management at a single centre between 2000 and 2011. Patients were identified through surgical logbooks. A subsequent case note-review identified 61 patients (80 procedures) with primary open angle glaucoma (POAG). The primary outcome was success of trabeculectomy surgery, with failure defined as intraocular pressure (IOP) > 21 mmHg, ≤ 5 mmHg or not reduced by 20% at two consecutive follow-up visits 3-months post-operatively. Qualified success was defined as surgical success with the use of supplemental medical therapy. Secondary outcomes included visual acuity, Humphrey visual field MD, surgical complications and post-operative interventions.
  
  
  RESULTS
  At 3 years, the odds ratio of failure was 0.93 per mmHg pre-operative IOP (95% C.I. 0.83-1.03, p = 0.15 Wald Χ (2) test), and the odds ratio of failure or qualified success was 0.96 (95% C.I. 0.89-1.04, p = 0.35). The incidence of surgical complications showed an odds ratio of 1.02 per mmHg pre-operative IOP (95% C.I. 0.95-1.10, p = 0.55 Wald Χ (2) test). The incidence of post-operative interventions showed an odds ratio of 1.01 per mmHg pre-operative IOP (95% C.I. 0.94-1.09, p = 0.80 Wald Χ (2) test).
  
  
  CONCLUSIONS
  Pre-operative IOP does not predict success of trabeculectomy surgery in POAG patients during the first 3 years of follow-up. The incidence of surgical complications and post-operative interventions shows no association with pre-operative IOP.
authors.affiliation: School of Clinical Medicine, University of Cambridge, Hills Road, Cambridge, CB2 0QQ, UK. nn252@cam.ac.uk.
authors.forename: Nisha
authors.initials: N
authors.lastname: Nesaratnam
authors.affiliation: Department of Ophthalmology, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Hills Road, Cambridge, UK. nicholas.sarkies@addenbrookes.nhs.uk.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Sarkies
authors.affiliation: Department of Ophthalmology, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Hills Road, Cambridge, UK. krgm2@cam.ac.uk.|John van Geest Centre for Brain Repair and Cambridge NIHR Biomedical Research Centre University of Cambridge, Cambridge, UK. krgm2@cam.ac.uk.
authors.forename: Keith R
authors.initials: KR
authors.lastname: Martin
authors.affiliation: Department of Ophthalmology, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Hills Road, Cambridge, UK. humma.shahid@addenbrookes.nhs.uk.
authors.forename: Humma
authors.initials: H
authors.lastname: Shahid
mesh_terms: D000368:Aged; D000959:Antihypertensive Agents / Q000008:administration & dosage; D005260:Female; D005500:Follow-Up Studies; D005902:Glaucoma, Open-Angle / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D007429:Intraocular Pressure / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D057234:Preoperative Period; D012189:Retrospective Studies; D014065:Tonometry, Ocular; D014130:Trabeculectomy; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology
chemical_list: D000959:Antihypertensive Agents