Immediate versus delayed dexamethasone implantation during vitrectomy for diabetic macular edema with secondary...

ObjectiveTo compare outcomes between immediate intraoperative dexamethasone implantation and scheduled 1-month postoperative dexamethasone implantation in pseudophakic eyes undergoing vitrectomy for diabetic macular edema with secondary epiretinal membrane.MethodsThis retrospective comparative study included 80 pseudophakic eyes with diabetic macular edema and secondary epiretinal membrane. All eyes underwent 25-gauge vitrectomy with epiretinal membrane and internal limiting membrane peeling. The Immediate Group $n=40$ received dexamethasone implantation at the end of vitrectomy, and the Delayed Group $n=40$ received the first dexamethasone implant 1 month postoperatively. From month 3, both groups followed the same pro re nata retreatment protocol. Best-corrected visual acuity, central macular thickness, intraocular pressure, and dexamethasone injection frequency were assessed for 12 months.ResultsBoth groups showed improvement in best-corrected visual acuity and reduction in central macular thickness, but early recovery was faster in the Immediate Group. At 1 month, best-corrected visual acuity was 0.55 ± 0.08 versus 0.78 ± 0.11 logarithm of the minimum angle of resolution, and central macular thickness was 315.5 ± 28.6 versus 520.2 ± 35.4 μm, respectively (both P < 0.001). Mixed-effects models showed significant time effects and significant group × time interactions at earlier visits, supporting greater early improvement in the Immediate Group. At 12 months, best-corrected visual acuity remained better in the Immediate Group (0.36 ± 0.08 vs. 0.43 ± 0.10 logarithm of the minimum angle of resolution, P = 0.001). Although central macular thickness remained lower in the Immediate Group, the group × time interaction for central macular thickness was no longer significant, indicating that the anatomical advantage became less pronounced over time. The Immediate Group showed numerically fewer dexamethasone injections, but without statistical significance. Intraocular pressure elevation was controlled medically, and no serious ocular or systemic adverse events were documented.ConclusionImmediate intraoperative dexamethasone implantation was associated with faster early anatomical recovery and earlier visual improvement. The anatomical advantage became less pronounced over time, and the potential effect on retreatment burden requires confirmation in prospective randomized studies.