Use of a dexamethasone implant to treat macular edema following pars plana vitrectomy and removal of the primary epiretinal membrane.

Purpose: The purpose of this study was to evaluate the effectiveness and safety of an intravitreal dexamethasone (DEX) implant for the treatment of macular edema (ME) following pars plana vitrectomy (PPV) and removal of the primary epiretinal membrane (ERM) and to assess the impact of the integrity of the ellipsoid zone (EZ) and disorganization of the retinal inner layer (DRIL) grade on visual and anatomical outcomes.

Methods: Forty-two pseudophakic patients who developed ME following PPV and removal of the primary stage 2-3 ERM were included. Patients were divided into two groups when ME was diagnosed via spectral domain optic coherence tomography (SD-OCT). In the DEX group (n = 22), DEX was implanted for the treatment of ME. In the control group (n = 20), only observation was conducted, without any treatment. The best-corrected visual acuity (BCVA) and macular thickness (MT) of the two groups were compared at baseline and 1, 6, and 12 months after DEX implantation. The effects of OCT parameters such as EZ integrity and DRIL grade were also evaluated in terms of decreases in MT and increases in VA in the treatment of ME with DEX implantation. Intraocular pressure (IOP), number of DEX implantations and adverse effects were also recorded.

Results: While a statistically significant increase in the mean BCVA was observed in the DEX group (p < 0.001 at months 1, 6, and 12, respectively), no such increase was detected in the control group (p = 0.169, p = 0.065, and p = 0.058 at months 1, 6 and 12, respectively) compared with the baseline. A statistically significant decrease in the mean MT was observed in the DEX group (p  < 0.001 at months 1, 6, and 12); however, no significant difference was observed in the control group (p  = 0.081, p  = 0.065, and p  = 0.054 at months 1, 6 and 12, respectively) compared with the baseline. Significant differences were found between the two groups in terms of the increase in BCVA (p  < 0.01) and decrease in MT (p  < 0.01) at all visits, with the outcomes being more favorable in the DEX group. A statistically significant relationship was found between the increase in VA and EZ integrity and DRIL grade in both groups. Ten patients (45.4%) received two injections of DEX during the follow-up. An increase in IOP was observed in five patients (22.7%) who were treated with topical antiglaucomatous drops. No significant side effects were observed.

Conclusion: DEX implantation was found to be effective and safe for the treatment of ME following PPV and primary ERM removal, although some eyes may require repeated injections to achieve visual and anatomical success. Additionally, a relationship was found between EZ integrity, DRIL grade and visual-anatomical outcomes.