Clinical Characteristics of Intermittent Exotropia in Children with Myopia and Myopic Anisometropia

Previous studies have yielded contradictory conclusions on the relationship between intermittent exotropia (IXT) and the magnitude of myopia, especially in children. The aim of this study was to determine the clinical characteristics of IXT in children with myopia and myopic anisometropia.

We retrospectively evaluated the clinical data of patients (4-15 years of age) with convergence insufficiency (CI)-IXT and basic IXT who underwent surgery between 2022 and 2023. All patients underwent cycloplegia before the examinations and surgery. The degree of strabismus was measured when the patient viewed from the center of the glasses. Ocular dominance was routinely tested in children with IXT via the "hole-in-card test" after best-corrected visual acuity was obtained. Children were subsequently grouped into 2 groups (anisometropia and nonanisometropia) according to the difference in binocular spherical equivalent (SE) values (≥ 1.0 diopters [D]).

A total of 197 patients were included in the study. The preoperative deviation at near was significantly lower in the basic IXT group than in the CI-IXT group, whereas the distance exodeviation was significantly greater in the basic IXT group than in the CI-IXT group (P < 0.05). Patients with anisometropia were older than those without anisometropia (P < 0.001). The dominant eyes had significantly less myopia than the nondominant eyes did in the CI-IXT and anisometropia groups (P = 0.049 and P = 0.003, respectively). High myopia was more prevalent in middle school students with IXT (16.67%) than in preschool students (4.55%) and primary schoolchildren (3.18%). The percentage of individuals with anisometropia (≥ 3.0 D) varied in the low (1.68%), moderate (8.7%), and high myopia groups (22.22%). Binomial logistic regression analysis revealed that age and SE of the dominant eye were independent factors related to anisometropia in children with IXT (P < 0.001 and P < 0.001, respectively).

Patients with IXT, especially those with anisometropia and CI-IXT, were shown to have less myopia in the dominant eye. Age and SE of the dominant eye were found to be independent factors related to anisometropia in children with IXT.