Correlation of Refractive Error with Anisometropia Development in Early Childhood

This study aims to investigate the relationship between the type and severity of refractive error and anisometropia development in preschool children.Retrospective cohort study.Data from Maccabi Healthcare Services, Israel's second-largest Health Maintenance Organization (HMO), were analyzed. The study included all isometropic children aged 1-6 years, re-examined for refraction at least two years following their initial examination between 2012 and 2022. Anisometropia was defined as a ≥1 diopter interocular difference in spherical equivalent. Relationships were assessed using logistic regression models adjusted for key sociodemographic factors.Among 33,496 isometropic children (51.2% male, mean age 3.2 ± 1.5 years), the prevalences of emmetropia, myopia, and hyperopia were 26.7% (n=8,944), 4.2% (n=1,397), and 69.1% (n=23,155), respectively. Over a mean follow-up period of 5.1 ± 2.4 years, 2,593 children (7.7%) were diagnosed with anisometropia. Adjusted odds ratios (ORs) for anisometropia gradually increased with baseline refractive error severity, reaching 13.90 (5.32-36.34) in severe myopia and 4.19 (3.42-5.15) in severe hyperopia. This pattern was also evident in cylindrical anisometropia, where ORs increased with greater baseline astigmatism, peaking at 12.10 (9.19-15.92) in children with high astigmatism (≥ 3 D). Associations remained consistent in sensitivity and subgroup analyses including across both genders and when using a stricter anisometropia criterion.Children aged 1-6 years, initially without anisometropia but showing increasing severity of myopia, hyperopia, or astigmatism, are more likely to develop anisometropia. This underscores the importance of follow-up refractive measurements within this population to promptly diagnose and treat anisometropia and prevent potential visual complications.