Vitrectomy for diabetic macular edema: a systematic review and meta-analysis.

OBJECTIVE: To systematically review, and perform meta-analysis on, the available data regarding the efficacy of vitrectomy for diabetic macular edema. DESIGN: Systematic review and meta-analysis of published randomized controlled trial data. METHODS: We searched PubMed and the Cochrane database for randomized, controlled trials investigating vitrectomy for diabetic macular edema. Structural (foveal thickness) and functional (visual acuity) outcomes were used as the primary outcome measures. RESULTS: Eleven studies met the criteria for inclusion in this review: these studies were heterogenous in their experimental and control interventions, follow-up period, and eligibility criteria. Seven studies compared vitrectomy with the natural history of diabetic maculopathy, with laser, or with intravitreal corticosteroid injection. Four studies compared vitrectomy with internal limiting membrane peeling to vitrectomy alone. One of the latter 4 studies was the only to investigate vitrectomy in patients with vitreomacular traction. Meta-analysis suggests a structural, and possibly functional, superiority of vitrectomy over observation at 6 months. Vitrectomy also appears superior to laser in terms of structural, but not functional, outcomes at 6 months. At 12 months, vitrectomy offers no structural benefit and a trend toward inferior functional outcomes when compared with laser. CONCLUSIONS: There is little evidence to support vitrectomy as an intervention for diabetic macular edema in the absence of epiretinal membrane or vitreomacular traction. Although vitrectomy appears to be superior to laser in its effects on retinal structure at 6 months, no such benefit has been proved at 12 months. Furthermore, there is no evidence to suggest a superiority of vitrectomy over laser in terms of functional outcomes