Distance-dependent changes in deviation control after alternate occlusion therapy in children with intermittent exotropia: a retrospective pilot study

Purpose: To evaluate distance-dependent changes in deviation control after alternate occlusion therapy in children with intermittent exotropia (IXT). Methods: This study included 15 patients (6 males and 9 females) aged 4 to 6 years who had undergone alternate occlusion therapy for more than 2 months at the Department of Ophthalmology, Kindai University Hospital between June 2022 and December 2023. Alternate occlusion was performed at a ratio of 1:1 or 2:1, and daily occlusion time was set to 4 to 6 hours. Patients’ control was evaluated at 30 cm, 1, 2, 3, 4, and 5 m and classified using Kushner’s 4-grade (Excellent, Good, Fair, Poor) classification method (2019). In this study, an excellent or good level of control was considered favorable and otherwise unfavorable. Control was evaluated at the start (baseline) and the end of the occlusion therapy. Factors for control improvement including the initial age, the occlusion duration, and the initial deviation angle were also analyzed. We further investigated if patients’ control varied with viewing distance by examining the viewing distance at which phoria could be maintained. Results: Of 15, 6 (40.0%) patients had unfavorable near control at baseline and 5 (83.3%) of them significantly improved control to a favorable level after occlusion (95% CI: 0.06–0.61). At distance, all 15 patients had unfavorable control at baseline and 5 (33.3%) patients significantly improved control to a favorable level after occlusion therapy (95% CI: 0.09–0.57). Logistic regression analysis revealed no significant factors influencing patients’ control improvement. Of 15, 14 patients could be examined for phoria maintenance at all viewing distances and 11 (78.6%) patients showed phoria maintenance in a significantly extended viewing distance after occlusion therapy (p < .01, Wilcoxon signed-rank test).In addition, the proportion of patients maintaining phoria significantly increased at 1 m and 2 m (p = .031 for both). Conclusion: Alternate occlusion therapy was associated with improved deviation control and an extension of the viewing distance over which phoria could be maintained in children with IXT, suggesting a distance-dependent pattern of improvement progressing from near to distance rather than uniformly across distances.