PARS PLANA VITRECTOMY FOR SYMPTOMATIC EPIRETINAL MEMBRANES IN EYES WITH 20/50 OR BETTER PREOPERATIVE VISUAL ACUITY. 
To evaluate pars plana vitrectomy with membrane peel for symptomatic epiretinal membranes in eyes with preoperative best-corrected visual acuity of 20/50 or better.  Patients with symptomatic epiretinal membrane and 20/50 or better vision who underwent pars plana vitrectomy with membrane peel by a single surgeon at our institution between January 2007 and January 2014 were identified.  The principal outcomes measured were best-corrected visual acuity and central subfield macular thickness at 1, 6, and 12 months of follow-up.  Subjective improvement in patient symptoms and complications were also documented.  Thirty-three eyes of 33 consecutive patients were included in this retrospective case series.  Mean preoperative best-corrected visual acuity was 20/40 and improved to 20/28 (P = 0.00008) at Month 12.  Mean central subfield macular thickness improved from 437 μm preoperatively to 391 μm by Month 1 (P = 0.00006) and 388 μm at 12 months (P = 0.00142).  Seventy-three percent (24 of 33) of patients (95% confidence interval: 55.6-85.1%) reported improvement of visual symptoms during the follow-up period.  Of the 13 patients who were phakic preoperatively, 6 patients (46.1%, 95% confidence interval: 23.2-70.9%) underwent phacoemulsification surgery within 1 year of vitrectomy.  Patients experienced a gradual gain in acuity and improvement of symptoms after pars plana vitrectomy with membrane peel.  Cataract progression necessitating cataract surgery is common in phakic patients.