Postoperative cystoid macular edema after pars plana vitrectomy for epiretinal membrane: incidence, anatomical and functional outcomes, and response to intravitreal dexamethasone implant.

Abstract

Background: To determine the incidence of postoperative cystoid macular edema (CME) following pars plana vitrectomy (PPV) with epiretinal membrane (ERM) peeling, and to evaluate the anatomical and functional response to intravitreal dexamethasone implant (Ozurdex; AbbVie) in affected eyes.

Methods: This retrospective, single-center cohort study included 92 consecutive eyes with idiopathic ERM that underwent PPV with ERM peeling by a single surgeon. Eyes were allocated to a control group (n = 84), comprising eyes without postoperative CME, or to a CME group (n = 8), comprising eyes that developed postoperative CME confirmed on swept-source optical coherence tomography (SS-OCT) and subsequently received intravitreal dexamethasone implant (DEX). Best-corrected visual acuity (BCVA, logMAR), central macular thickness (CMT, µm), and intraocular pressure (IOP, mmHg) were assessed preoperatively and postoperatively in both groups, and before and after DEX implantation in the CME group.

Results: The incidence of postoperative CME requiring treatment was 8.7%. Most baseline characteristics were comparable between groups, although preoperative IOP was significantly lower in the CME group. CMT decreased significantly after surgery in both the control group (335.1 ± 37.3 to 289.5 ± 22.9 μm; p < 0.001) and the CME group (382.9 ± 74.6 to 310.9 ± 22.9 μm; p = 0.033); however, postoperative CMT remained significantly higher in the CME group than in controls (p = 0.034). DEX implantation produced an additional significant CMT reduction (379.9 ± 67.1 to 302.7 ± 35.3 μm; p = 0.003), reducing the between-group difference to a non-significant level (p = 0.332). BCVA improved significantly after surgery in the control group (0.32 ± 0.26 to 0.04 ± 0.10 logMAR; p < 0.001) but not in the CME group (p = 0.582). Following DEX implantation, BCVA improved significantly in the CME group (0.47 ± 0.35 to 0.22 ± 0.25 logMAR; p = 0.002), approaching values observed in the control group (p = 0.078). IOP remained stable in controls (p = 0.576). A transient but significant IOP increase was observed in the CME group after surgery (11.5 ± 2.7 to 15.3 ± 3.7 mmHg; p = 0.019), with no further change after DEX implantation (p = 0.747).

Conclusions: Postoperative CME requiring treatment occurred in approximately 1 in 11 eyes following PPV with ERM peeling and was associated with significant anatomical and functional impairment. The present findings suggest that intravitreal dexamethasone implant was associated with improvement in selected cases of postoperative CME without additional impact on IOP; however, larger prospective studies are required to confirm these results.