Correlation of Refractive Error with Anisometropia Development in Early Childhood.

Purpose: This study aims to investigate the relationship between the type and severity of refractive error and anisometropia development in preschool children.

Design: Retrospective cohort study.

Methods: Data from Maccabi Healthcare Services, Israel's second-largest Health Maintenance Organization (HMO), were analyzed. The study included all isometropic children aged 1 to 6 years, re-examined for refraction at least 2 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.

Results: 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 = 8944), 4.2% (n = 1397), and 69.1% (n = 23,155), respectively. Over a mean follow-up period of 5.1 ± 2.4 years, 2593 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 sexes and when using a stricter anisometropia criterion.

Conclusions: Children aged 1 to 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.