Efficacy of Intravitreal Dexamethasone Implant in Persistent DME by ERM Status

To determine whether the presence of an epiretinal membrane (ERM) predicts treatment outcomes following intravitreal dexamethasone implant (DEX) in eyes with persistent diabetic macular edema (DME).

This is a retrospective cohort study of patients with persistent DME seen at a single academic center over a 10-year period from 2014-2025. Persistent DME was defined as retinal thickness greater than 300 microns despite anti-VEGF treatment for at least 6 months and three injections. Patients were excluded for non-diabetes causes of secondary ERM, vitreomacular adhesion or traction, prior steroid treatment or vitreoretinal surgery, or recent laser or other surgery. Forty-seven eyes from 41 patients met the inclusion criteria. Eyes were categorized based on ERM status, and outcomes were compared. The primary outcomes were changes in best-corrected visual acuity (BCVA) and central subfield thickness (CST) from baseline to 3 and 6 months following DEX.

Twenty-six of 47 (55%) eyes had an ERM. Demographics, treatment history, and baseline anatomic characteristics were similar between the ERM and non-ERM groups. Baseline BCVA was worse in the ERM group. Patients with an ERM trended toward greater improvement in visual acuity following DEX than patients with no ERM; however, this difference was not statistically significant. Similarly, improvements in CST, center maximum thickness, and retinal volume were greater in the ERM group but failed to reach statistical significance.

The presence of an ERM was associated with directionally greater visual and anatomic improvements following DEX treatment, however this was not statistically significant after accounting for baseline CST, baseline BCVA, PDR, and prior PRP.