title: PARS PLANA VITRECTOMY FOR DIABETIC MACULAR EDEMA: A Systematic Review, Meta-Analysis, and Synthesis of Safety Literature.
abstract: OBJECTIVE
  To assess the risk and benefit of pars plana vitrectomy for diabetic macular edema.
  
  
  METHODS
  The authors conducted a systematic literature review using PubMed, EMBASE, Web of Science, and Cochrane Central Database of Controlled Trials until September 2014. The population was patients with diabetic macular edema, intervention vitrectomy, comparator macular laser or observation, and efficacy outcome visual acuity and central retinal thickness. Safety outcomes were intraoperative and postoperative surgical complications. The efficacy meta-analysis included only randomized controlled trials. The safety analysis included prospective, retrospective, controlled, and uncontrolled studies.
  
  
  RESULTS
  Five studies were eligible for the efficacy meta-analysis (n = 127 eyes) and 40 for the safety analysis (n = 1,562 eyes). Combining follow-up intervals from 6 to 12 months, the meta-analysis found a nonsignificant 2 letter visual acuity difference favoring vitrectomy, and a significant 102 μm greater reduction in central retinal thickness favoring vitrectomy, but a post hoc subgroup analysis found that a 6-month central retinal thickness benefit reversed by 12 months. The most frequent complications were retinal break (7.1%), elevated intraocular pressure (5.2%), epiretinal membrane (3.3%), and vitreous hemorrhage (2.4%). Cataract developed in 68.6% of 121 phakic eyes.
  
  
  CONCLUSIONS
  Vitrectomy produces structural and functional improvements in select eyes with diabetic macular edema, but the visual gains are not significantly better than with laser or observation. No major safety concerns were identified.
authors.affiliation: *Department of Ophthalmology, King's College Hospital, School of Medicine, King's College London, London, United Kingdom; and †LSE Health, London School of Economics and Political Science, London, United Kingdom.
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Jackson
authors.forename: Elena
authors.initials: E
authors.lastname: Nicod
authors.forename: Aris
authors.initials: A
authors.lastname: Angelis
authors.forename: Federico
authors.initials: F
authors.lastname: Grimaccia
authors.forename: Edward
authors.initials: E
authors.lastname: Pringle
authors.forename: Panos
authors.initials: P
authors.lastname: Kanavos
mesh_terms: D003930:Diabetic Retinopathy / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D008266:Macula Lutea / Q000473:pathology; D008269:Macular Edema / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D014792:Visual Acuity / Q000502:physiology; D014821:Vitrectomy / Q000009:adverse effects / Q000379:methods*