Results and prognostic factors for visual improvement after pars plana vitrectomy for idiopathic epiretinal membrane.

Background: Pars plana vitrectomy (PPV) for peeling epiretinal membrane is now generally recommended with better vision compared with historical series. This study reports the results and prognostic factors for postoperative visual improvement in a contemporary series. Methods: Demographic data, best-corrected visual acuity (BCVA), and optical coherence tomography parameters of 504 eyes (495 patients) that underwent PPV for idiopathic epiretinal membrane from 2003 to 2012 were tabulated. The primary outcome measure was proportion of eyes with improvement of at least two Snellen lines or more of BCVA 3, 6, and 12 months after PPV. A secondary outcome was prognostic factors for improvement of at least two Snellen lines or more of BCVA after PPV at 3, 6, and 12 months. Results: There was a gain of >= 2 lines in 211 of 504 eyes (41.7%) at 3 months, in 84 of 242 eyes (34.7%) at 6 months, and 112 of 233 eyes (48.1%) at 12 months after PPV and epiretinal membrane peeling surgery. Poorer preoperative BCVA and preoperative pseudophakic lens status were associated with better visual improvement at 3 months. Conclusion: The lower frequency of moderate BCVA improvement for those with good preoperative BCVA and phakic lens status might influence visual improvement, and therefore, a recommendation for surgery.