Children with intermittent exotropia (IXT) may not be significantly more myopic than their peers, but they appear substantially more likely to develop anisometropia as they age, according to a large nationwide Korean study published in Scientific Reports.
The study, which analyzed refractive profiles from 2,744 children with IXT and compared them with 1,224 participants from the Korean National Health Examination Survey (KNHANES), challenges longstanding assumptions that myopia is intrinsically linked to exotropia severity.
“Children with IXT show a higher prevalence of anisometropia but not a significantly higher incidence of myopia compared to the general population,” the investigators concluded.
Intermittent exotropia is among the most common forms of childhood strabismus in East Asia, where myopia prevalence is also exceptionally high. Because myopia reduces accommodative demand – and therefore accommodative convergence – researchers have long speculated that it may contribute to exotropic drift.
To explore the relationship in greater detail, investigators used data from the Korean Intermittent Exotropia Multicenter Study (KIEMS), a nationwide consortium involving 53 institutions and 65 strabismus specialists. The analysis focused on children aged 5–18 years without amblyopia and compared cycloplegic refractive findings with population-level refractive data from KNHANES.
Despite the large number of myopic children in the IXT cohort, age-specific refractive error distributions closely mirrored those of the general population – spherical equivalent values in both more myopic and less myopic eyes followed similar trajectories across childhood and adolescence in both datasets.
The study also found that non-dominant eyes in children with IXT tended to become progressively more myopic than dominant eyes after age nine. However, these non-dominant eyes still did not exceed the degree of myopia observed in the more myopic eyes of the general population.
The authors suggest the findings may indicate that IXT contributes less to overall myopia development than previously suspected, but may instead influence asymmetric ocular growth between eyes.
The study’s retrospective and cross-sectional design limits conclusions about causality, and the study authors acknowledge differences in refractive measurement techniques between datasets. Still, the work represents one of the largest analyses to date examining refractive characteristics in pediatric intermittent exotropia.
