Pars Plana Vitrectomy with Internal Limiting Membrane Peeling for Refractory Diffuse Diabetic Macular Edema

Purpose: To evaluate the effect of pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling for management of refractory diffuse diabetic macular edema (DME). Methods: In this prospective interventional case series, eyes with refractory diffuse DME unresponsive to macular photocoagulation and/or intravitreal bevacizumab, and best corrected visual acuity (BCVA) ≥20/200 and ≤20/60 underwent triamcinoloneassisted PPV with ILM peeling. Pre- and postoperative evaluations included a complete ophthalmologic examination, fluorescein angiography and optical coherence tomography (OCT). Main outcome measures were BCVA and central macular thickness (CMT). Results: Twelve eyes of 12 patients with mean age of 59.6±3.9 (range, 55-68) years were operated and followed for a mean period of 4.9±1.0 (range, 4-6) months. Mean BCVA at final examination was 0.82 ± 0.18 logMAR which was not significantly better than its preoperative value of 1.00 ± 0.80 logMAR (P=0.959). Visual acuity improved by at least 2 lines in 3 eyes (25%), remained stable in 7 eyes (58%) and decreased by at least 2 lines in 2 eyes (17%). Mean CMT at final examination was 315±95 μm, which was significantly less than its preoperative value of 467±107 μm (P=0.004). Complications included vitreous hemorrhage in 2 and cataract progression in 5 eyes. Conclusion: PPV with ILM peeling for refractory diffuse DME seems to reduce macular thickness, but does not significantly improve visual acuity as observed after an intermediate-term follow up of about 6 months.