Hyperreflective Foci in the Ectopic Inner Foveal Layer of Advanced Idiopathic Epiretinal Membranes.

Purpose: To investigate the presence of hyperreflective foci (HF) in the ectopic inner foveal layer (EIFL) of eyes with advanced idiopathic epiretinal membranes (iERMs) before and after pars plana vitrectomy (PPV) with ERM peeling. Methods: A retrospective analysis was conducted on clinical records and spectral-domain optical coherence tomography (SD-OCT) scans from consecutive patients who underwent PPV with ERM peeling. Stage 3 and stage 4 iERMs were included. HF were defined as dot-like lesions (<30 µm) with reflectivity similar to that of the retinal nerve fiber layer, lacking backshadowing, located in the EIFL thickness within 1500 µm of the fovea. Patients were followed up to twelve months after surgery. Results: A total of 47 eyes were included: 10 stage 4 iERM and 37 stage 3 iERM. HF in EIFLs were observed in 74.5% of cases, with higher prevalence in stage 4 than stage 3 (100% vs. 67.6%; P = 0.035). At baseline, an increase in HF count was associated with greater EIFL thickness (r = 0.497, P < 0.001). At 7.8 ± 1.8 months post-surgery, HF were found in 59.6% of eyes. Eyes with persistent HF had greater postoperative EIFL thickness than those without (143 ± 60.4 vs. 103.7 ± 57.3; P = 0.036). In multivariate linear regression, the presence of HF at baseline (β = 0.373, P = 0.048) was significantly associated with worse postoperative visual acuity. Conclusions: HF in the EIFL were more prevalent in advanced iERM and correlated with increased EIFL thickness. Their presence at baseline was associated with worse postoperative visual acuity.