Comparison of different surgery procedures for convergence insufficiency-type intermittent exotropia in children

Aims To compare prospectively the surgical outcomes of different surgery procedures for convergence insufficiency (CI)-type intermittent exotropia (IXT) in children. Methods Forty-five children with CI-type IXT were included in this prospective surgical study with 6 months follow-up. According to the different surgical procedures, all children were randomly divided into three groups: the unilateral medial rectus resection (UMR) group (15 cases), the bilateral medial rectus resections (BMR) group (14 cases) and the improved unilateral recession-resection (R&R) group (16 cases). In the UMR and BMR groups, the medial rectus resection(s) were based on the distance exodeviation. In the R&R group, UMR was based on the near exodeviation while lateral rectus recession was based on the distance exodeviation. A successful surgical alignment was defined as the distant deviation in the primary gaze to be between ≤10 prism dioptres (PD) of exophoria/tropia and ≤5 PD of esophoria/tropia. The success rate, the preoperative and postoperative deviations at distance and near and near-distance differences among groups were compared. Results At the last follow-up of 6 months, the success rate in the R&R (87.5%) group was significantly higher than those in the UMR (13.3%) and BMR (42.9%) groups (p=0.000 and 0.008); the mean exodeviations at distance and near in the R&R group were significantly different from those in the UMR and BMR groups (p=0.000 and 0.001); there were no significant differences in the mean near-distance differences between the R&R group and the other two groups (p>0.05). Conclusions The improved R&R procedure in which medial rectus resection based on the near deviation with lateral rectus recession based on the distant deviation has a better alignment than the UMR and BMR surgeries for the treatment of children with CI-type IXT. All the UMR, BMR and improved R&R surgery can reduce near-distance differences in children with CI-type IXT.