Impact of Axial Length on Visual Outcomes and OCT Findings in Epiretinal Membrane: A Retrospective Study

Background: Axial elongation may influence the structural characteristics and surgical prognosis of epiretinal membrane (ERM), but its impact across different axial length (AL) categories remains unclear. Methods: We retrospectively analyzed 557 eyes from 515 patients with ERM who underwent vitrectomy and were followed for at least 6 months. Eyes were stratified by AL into normal to mild myopia (NM; <26 mm), high myopia (HM; ≥26 to <28 mm), and extreme high myopia (EHM; ≥28 mm). Clinical variables included age, AL, and pre- and postoperative best-corrected visual acuity (BCVA). OCT parameters assessed included inner and outer retinal cystoid lesions, epiretinal proliferation (EP), and ellipsoid zone (EZ) disruption. Results: Postoperative BCVA significantly improved in the NM and HM groups (p < 0.001) but not in the EHM group (p = 0.091). Although preoperative BCVA was comparable among groups, postoperative BCVA was significantly better in the HM group (-0.02 ± 0.17 logMAR) compared with the NM (0.03 ± 0.20 logMAR) and EHM (0.21 ± 0.43 logMAR) groups (p < 0.05). Outer retinal cystoid lesions were significantly more frequent in the EHM group (p < 0.05), whereas the prevalence of EZ disruption, inner retinal cystoid lesions, and EP did not differ significantly among groups. Conclusions: Eyes with ERM and extreme high myopia exhibited limited postoperative visual improvement and a higher prevalence of outer retinal cystoid lesions, suggesting that axial elongation may adversely affect surgical prognosis.