Cystoid macular edema after vitrectomy and after phacovitrectomy for epiretinal membrane

Objective To compare the incidence of cystoid macular edema (CME) after vitrectomy and CME after phacovitrectomy in patients requiring epiretinal membrane (ERM) removal. Design A retrospective, comparative, interventional study. Methods Medical records of patients who had undergone vitrectomy or phacovitrectomy for ERM removal by a single surgeon were retrospectively reviewed. Phacovitrectomy was performed in all phakic eyes and vitrectomy was performed in all pseudophakic eyes. Increased macular thickness (IMT) was defined as an increase in macular thickness by more than 10% at the postoperative week 4 visit compared to the measurements at baseline. Results There were 214 and 53 eyes in the Phacovitrectomy group and the Vitrectomy group, respectively. IMT occurred in 15.4% of the Phacovitrectomy group, which was higher than the incidence of 3.8% in the Vitrectomy group (p=0.023). Conclusions IMT, that is suspected to be a type of CME, was not uncommon (15.4%) after phacovitrectomy in phakic eyes but was uncommon (4.8%) after vitrectomy alone in pseudophakic eyes. Irvine-Gass syndrome appears to be triggered by crystalline lens removal itself rather than intraocular surgery or surgical trauma alone.