Anatomic and functional outcome after surgical removal of idiopathic macular epiretinal membrane

The purpose of this study is to investigate the functional and structural outcomes of surgical treatment of eyes with idiopathic macular epiretinal membrane (ERM). Clinical records of 21 patients (22 eyes) who underwent macular ERM removal with at least 6 months of postoperative follow-up period were reviewed retrospectively. All patients were treated with pars plana vitrectomy and ERM peeling surgery. Fourteen patients also underwent cataract surgery at the same time. Pre- and postoperative visual acuity (VA), intraocular pressure (IOP), and macular thickness along with postoperative adverse events were all recorded. The mean follow-up was 8.5 ± 3.2 months. Three eyes were pseudophakic and 19 eyes were phakic preoperatively. Five phakic eyes undergoing simple ERM peeling surgery had worsened cataracts, and vision was recovered after subsequent cataract extraction surgery. Mean preoperative IOP was 13.1 ± 4.2mmHg, which did not differ significantly postoperatively (p=0.228). One patient had increased IOP postoperatively and needed topical antiglaucoma treatment. Thirteen eyes showed visual improvement, and six eyes became worse during the follow-up. Mean preoperative best-corrected VA was 0.36 decimal equivalent, which was then converted to logarithm of the minimum angle of resolution (logMAR 0.502 ± 0.259) for statistical analysis; this had improved to a mean of 0.536 decimal equivalent (logMAR 0.38 ± 0.35) at the final follow-up. Mean central macular thickness (CMT) also significantly declined (p<0.0001). From an analysis of dividing patients into two subgroups according to clinical severity [macular pucker (MP) and cellophane maculopathy (CM)], measured mean CMT of both groups demonstrated significant reduction at final follow-up (MP, p<0.0001; CM, p=0.005). Mean final best-corrected VA also reached significant improvement in MP group (p=0.008). However, in the CM group, no significant change in VA was observed (p=0.52). Besides, VA measurements in the MP group had improved significantly to that of CM (p=0.037). The measured CMTs of the MP group had also reduced significantly (p=0.046) compared with those of the CM group. In conclusion, membrane peeling surgery can lead to a significant reduction of macular edema in patients with idiopathic macular ERM. The advantages of combined peeling and cataract surgery will achieve maximum positive visual outcome.