Evaluation of Functional Outcomes and OCT-Biomarkers after Intravitreal Dexamethasone Implant for Postoperative Cystoid Macular Edema in Vitrectomized Eyes

PURPOSE: To evaluate the efficacy of dexamethasone implant (DEX) for the treatment of postoperative cystoid macular edema (PCME) in vitrectomized eyes and to investigate visual and morphological OCT predictive factors. METHODS: In this retrospective study, eyes with PCME after vitrectomy were treated with at least one DEX injection and were observed over 12 months. Indications for surgery were epiretinal membrane (ERM) or rhegmatogenous retinal detachment (RRD) without macular involvement. Prior treatments, if any, were noted. Best corrected visual acuity (BCVA), central foveal thickness (CFT), and OCT morphology including the presence of intraretinal cysts/fluid or subretinal fluid (IRF/SRF) and ellipsoid zone (EZ) continuity were evaluated. Correlations between OCT measures and visual outcomes were analyzed by the generalized estimating equations procedure. RESULTS: Forty-six eyes with ERM and 15 eyes with RRD were enrolled. The ERM group was more likely to gain BCVA than RRD (odds ratio (OR), 1.168; 95% confidence interval (CI), 1.003–1.360; p=0.046). The absence of SRF (OR, 0.860; 95% CI, 0.743–0.995; p=0.043) was predictive of worse BCVA, whereas the integrity of EZ (OR, 1.094; 95% CI, 0.951–1.257; p=0.209) or naïve status (OR, 0.946; 95% CI, 0.871–1.137, p=0.853) was not. Eyes with a worse baseline BCVA were more likely to gain >1 line after 12 months (OR, 1.485; 95% CI, 1.171–1.884; p=0.001). CONCLUSION: The efficacy of the treatment of PCME in vitrectomized eyes seems to be affected by baseline BCVA, the absence of SRF, and the indication for surgery. Naïve status appears not to play any significant role in the prediction of BCVA. This trial is registered with DRKS00018955.