Visual outcomes of primary versus secondary epiretinal membrane following vitrectomy and cataract surgery

Purpose: To compare visual outcomes, incidence of cystoid macular edema (CME), and rate of repeat epiretinal membrane (ERM) surgery following phacovitrectomy for primary and secondary ERM. Methods: Retrospective review of 178,856 cataract surgeries from 2003 to 2015. Eyes that underwent cataract surgery combined with ERM peel were included (n = 708). Eyes were divided into primary (n = 538) and secondary (n = 170) ERM groups. Patient demographics, visual acuity (VA), and postoperative CME were recorded. Results: Patients with secondary ERM had worse preoperative VA, 0.9 ± 0.6 logMAR (20/160 Snellen equivalent) as compared to patients with primary ERM, 0.6 ± 0.3 (20/80), respectively (p < 0.0001). There was no difference between the secondary and primary ERM groups in postoperative vision (0.5 ± 0.4 logMAR vs. 0.5 ± 0.3; p = 0.9962) or proportion with VA ≥ 20/40 (46.4% vs. 43.1%; p = 0.6744) at 12–24 weeks. Postoperative CME was twice as likely in the secondary ERM group (16.5%) compared to the primary ERM group (7.8%) (p = 0.0018). There was no difference in the rate of repeat ERM surgery between the secondary ERM group (1.8%) and the primary ERM group (1.5%) (p = 0.7308). Conclusion: Eyes with secondary ERM had significant postoperative improvement in VA. They had worse preoperative VA and had a twofold increase in postoperative CME than primary ERM.