Incidence of Idiopathic Epiretinal Membrane and Its Association with Refractive Errors in an Elderly Cohort: A Retrospective Cohort Study

Purpose: This study aimed to investigate the association between refractive status and the incidence of idiopathic epiretinal membrane (iERM) in adults aged ≥ 50 years. Methods: This retrospective cohort study included 1463 participants (2926 eyes) without epiretinal membrane at baseline from a health-examination population at East China Sanatorium (2016–2021). Spherical equivalent (SE) from non-cycloplegic autorefraction was categorized as moderate-to-high myopia (SE < −3.00 D), low myopia (−3.00 D ≤ SE ≤ −0.50 D), emmetropia (−0.50 < SE < +0.50 D; reference), or hyperopia (SE ≥ +0.50 D). iERM was diagnosed by ophthalmoscopy and spectral-domain optical coherence tomography. Eye-level Cox models with participant-clustered robust variance were used. Results: During a median follow-up of 2.8 years, 158 eyes of 137 participants developed iERM (18.3 per 1000 eye-years). The incidence was 28.3, 21.7, 12.7, and 16.2 per 1000 eye-years in the moderate-to-high myopia, low myopia, emmetropia, and hyperopia groups, respectively. After multivariable adjustment, moderate-to-high myopia (hazard ratio 2.67; 95% CI 1.55–4.60) and low myopia (1.74; 1.03–2.92) were associated with a higher risk of iERM, whereas hyperopia was not (0.97; 0.59–1.59). Astigmatism type was not significantly associated with iERM, and no statistically significant interaction with age or sex was detected. Conclusions: More myopic SE was associated with a higher hazard of iERM, whereas the categorical analysis did not show a lower hazard in hyperopic eyes. Studies incorporating axial length and vitreous status are needed to clarify the underlying mechanisms.