Outcomes of pars plana vitrectomy for the treatment of persistent diffuse diabetic macular edema

Aim The aim of this study was to evaluate surgical outcome of pars plana vitrectomy on patients with persistent diffuse diabetic macular edema (dDME) in the presence or absence of complete posterior vitreous detachment (PVD).Patients and methods Pars plana vitrectomy was performed on 37 eyes of 37 patients with dDME. They were divided into two groups: group I consisted of 21 eyes of 21 patients with dDME and attached posterior vitreous face. Group II consisted of 16 eyes of 16 patients with dDME and detached posterior vitreous face. Both visual acuity (VA) as logMAR values and central macular thickness using optical coherence tomography were measured before,1, 3, and 6 months postvitrectomy.Results The baseline VA was 0.8±0.17 and 0.7±0.39 logMAR in groups I and II, respectively. One month after vitrectomy, VA significantly improved to 0.5±0.23 (P=0.002) and to 0.5±0.24 (P=0.015) in groups I and II, respectively. The VA was 0.4±0.13 (P=0.001), 0.5±0.19 (P=0.003) 3 months postvitrectomy and was 0.4±0.25 (P=0.005) and 0.5± 0.22 (P=0.014) after 6 months in groups I and II, respectively. The mean foveal thickness before surgery was 598.6±105.4 and 520.87±103.15 µm in groups I and II, respectively. After 3 months it significantly improved to 235.25±110.2 µm (P=0.0001) and 280.23±112.3 µm (P=0.002), whereas after 6 months it was 220.13±98.15 and 270.62±85.15 µm in groups I and II, respectively.Conclusion Vitrectomy with removal of the posterior hyaloid face and the premacular vitreous pocket may achieve resolution of dDME and improve vision in some patients who failed to respond to conventional treatment. The visual and anatomical outcomes seem to be better in eyes with early stages of diabetic macular edema and good preoperative VA.