Characteristics of refractive errors in children with intermittent exotropia compared with the general population

This study compared refractive errors in children with intermittent exotropia (IXT) against the general population using two large nationwide datasets: the Korean Intermittent Exotropia Multicenter Study (KIEMS), involving 2,744 patients aged 5-18 years, and the Korean National Health Examination Survey (KNHANES), involving 1,224 participants. Age-specific spherical equivalent (SE) distributions in IXT patients were generally similar to the general population. While the non-dominant eye in IXT patients tended to be more myopic than the dominant eye, it did not exceed the myopia levels observed in the more myopic eyes of the general population. However, IXT patients exhibited a significantly higher rate of anisometropia, particularly in those older than 9 years (P<0.001). Linear regression analysis revealed that refractive profiles, including SE and interocular differences, had a very weak linear relationship with exotropia angles ($R^2=0.000-0.005$). Additionally, convergence insufficiency type IXT was more myopic than other types, while poor distance control was associated with less myopia (P<0.05). In conclusion, children with IXT show a higher prevalence of anisometropia but not a significantly higher incidence of myopia compared to the general population. Furthermore, refractive profiles in IXT are not strongly correlated with the magnitude of exotropia angle.