Large Korean Study Maps How Intermittent Exotropia Differs by Age at Presentation

A nationwide multicenter cross-sectional study of 5,385 Korean patients with intermittent exotropia (IXT) has documented how the clinical picture of this common strabismus varies with the age at which patients present. The research, published in BMC Ophthalmology, grouped patients into four age bands and compared their deviation measurements, refractive error patterns, sensory findings and symptoms, offering one of the largest clinical datasets on IXT to date.

The study included patients with an angle of exodeviation of at least 8 prism diopters (PD) at distance or near fixation, recruited between March 2019 and February 2020. Participants were divided into Group 1 (younger than 3 years), Group 2 (3 to under 10 years), Group 3 (10 to under 19 years) and Group 4 (19 years and older). Clinical manifestations and subjective symptoms were then compared across these groups.

Deviation angles were largest in the oldest group, averaging 30.95 ± 17.02 PD at distance and 33.52 ± 17.01 PD at near.

The basic type of IXT was the most common pattern in every age group, but subtype distribution shifted with age. Divergence excess type was more frequent in the youngest group, appearing in 8.1% of those patients, while convergence insufficiency type became more common later in life, affecting 19.8% of adolescents and 14.8% of adults.

Oblique muscle dysfunction was least frequent in the youngest group, at 17.4%, and most frequent in adults, at 34.5%. Abnormal head posture and complaints of subjective symptoms also tended to increase with age at presentation, suggesting that both motor complications and symptomatic burden accumulate as patients grow older.

Not every measured feature varied with age. Stereopsis results, a family history of strabismus, and a history of perinatal complications did not differ significantly across the four age groups, indicating that these characteristics appear relatively stable features of the IXT population regardless of when patients first present to care.

Another demographic pattern emerged from the sex distribution: the proportion of female patients was higher in the two younger groups.

The authors emphasize that, as a cross-sectional study, the analysis captures patients at a single point in time rather than following individuals over years, so the age-group differences describe presentation patterns rather than proven progression within individual patients. Even so, the scale of the cohort, drawn from multiple centers across Korea, gives the findings substantial weight. The researchers conclude that this is one of the largest clinical studies on IXT, identifying a range of age-related characteristics that may help clinicians anticipate the deviation type, refractive profile, motor findings and symptom burden they are likely to encounter in patients of different ages.

Subject of Research: Age-related clinical characteristics of intermittent exotropia in a large Korean cross-sectional cohort

Article Title: Clinical characteristics of intermittent exotropia in 5,385 Koreans by age at presentation: a nationwide multicenter, cross-sectional study

Article References: Joo, H. J., Ryu, W. Y., Choung, H., Kim, S.-J., Jeon, H., Shin, H. J., Han, S. Y., Heo, H., & Baek, S.-H. (2026). Clinical characteristics of intermittent exotropia in 5,385 Koreans by age at presentation: a nationwide multicenter, cross-sectional study. BMC Ophthalmology. https://doi.org/10.1186/s12886-026-05447-8

Image Credits: AI Generated

DOI: 10.1186/s12886-026-05447-8

Keywords: intermittent exotropia, strabismus, cross-sectional study, prism diopters, refraction, stereopsis, convergence insufficiency, divergence excess, oblique dysfunction, pediatric ophthalmology, Korea, Clinical