Virtual Reality-Based Vision Therapy for Intermittent Exotropia: A Randomized Clinical Trial.

Importance: Intermittent exotropia (IXT), the most common childhood divergent strabismus, disrupts binocular vision and psychosocial function. Objective: To assess the efficacy and safety of virtual reality-based vision therapy (VRVT) in children with IXT. Design, Setting, and Participants: This randomized clinical trial consists of a 12-week treatment phase (completed) and a 12-month follow-up phase (ongoing). The treatment phase was conducted from July 1, 2023, to November 17, 2024, in 3 tertiary hospitals in China. Eligible participants were children aged 6 to 18 years with previously untreated IXT, an exodeviation magnitude of 10 to 30 prism diopters at distance, an exotropia control score of 1 to 3 at both distance and near, and a cycloplegic spherical equivalent between -6.00 diopters (D) and +0.50 D in both eyes, with an interocular spherical equivalent difference of less than 2.50 D. Intervention: Participants were randomly assigned in a 1:1 ratio to the intervention group or control group. Participants in the intervention group underwent the home-based VRVT program for 12 weeks. Participants in the control group were observed but received no VRVT intervention. Main Outcome and Measure: The primary outcome was the change in distance exotropia control score from baseline to week 12. The Mann-Whitney test and Hodges-Lehmann estimator were used for between-group comparisons. Data analysis followed the modified intention-to-treat approach. Results: A total of 177 participants (median [IQR] age, 8 [7-10] years; 95 males [53.7%]) were randomized, of whom 161 were included in the full analysis set. At week 12, the median (IQR) change in distance exotropia control score was -0.33 (-1.00 to 0.00) in the intervention group vs 0.00 (-0.33 to 0.33) in the control group (between-group difference, -0.33; 95% CI, -0.57 to -0.10). Participants with greater than 75% VRVT training adherence had a greater improvement in distance exotropia control score than the control group (between-group difference, -0.71; 95% CI, -1.10 to -0.33). A significant interaction was identified between baseline distance exotropia control score and treatment effect (P for interaction = .01); greater improvement was observed in participants with a baseline score of 2 or higher (between-group difference, -0.67; 95% CI, -1.00 to -0.33), whereas minimal effect was seen in those with a score of 1 (between-group difference, -0.01; 95% CI, -0.23 to 0.20). No intervention-related adverse events were reported. Conclusions and Relevance: In this randomized clinical trial, the improvement in distance exotropia control over 12 weeks was modest. However, greater benefits were observed in participants with greater than 75% VRVT training adherence, which may indicate clinical value for children able to maintain high training adherence. Trial Registration: Chinese Clinical Trial Registry Identifier: ChiCTR2300072912.