Incidence and risk factors for epiretinal membrane formation after intravitreal anti-VEGF injection in branch retinal vein occlusion

Background/aims To determine the incidence and risk factors for epiretinal membrane (ERM) development following intravitreal anti-vascular endothelial growth factor (VEGF) injections in eyes with a branch retinal vein occlusion (BRVO). Methods This was a retrospective study that included patients with BRVO who received at least one anti-VEGF injection and were followed for ≥12 months at the Mie University Hospital between January 2018 and February 2024. Eyes with baseline ERM were excluded. Spectral-domain optical coherence tomography was used to determine the presence of an ERM and a posterior vitreous detachment (PVD) before and after the anti-VEGF injections. Post-injection PVD was defined as new-onset complete PVD in eyes without baseline complete PVD. Images were assessed by two experienced ophthalmologists. Clinical and systemic variables were analysed. Independent risk factors were identified using Firth’s penalised logistic regression. Results 100 eyes from 100 patients were analysed. ERM developed in 22 eyes (22%) within one year with a mean detection time of 18.0 ± 13.9 weeks. Post-injection PVD occurred in 36.4% of the ERM(+) group versus 5.1% of the ERM(−) group (p<0.001). In multivariable Firth models, post-injection PVD was consistently associated with ERM development (p≤0.01 across models). Baseline central macular thickness was greater in the ERM(+) group, but it was not independently associated with ERM development after adjustments. Conclusions About one-fifth of BRVO eyes developed an ERM within one year after anti-VEGF therapy. Post-injection PVD was the most robust factor associated with ERM development, underscoring the importance of vitreoretinal interface changes in the post-treatment course.