Dose-Response of Primary Bilateral Medial Rectus Resection in Infantile Exotropia

Purpose: To evaluate the dose-response relationship for primary bilateral medial rectus resection in children with exotropia, based on outcomes with this procedure. Methods: Dose-response at both distance and near were calculated as prism diopters correction per millimeter (PD/mm) of rectus resection. All surgeries were performed under general anesthesia through a fornix incision, using doubled-armed 6-0 polyglactin sutures. The resection amount ranged from 5 to 8 mm in each eye, according to the surgical dosage based on the largest angle of preoperative deviation. Results: The mean surgical dose-response for all procedures was 2.83 ± 1.03 PD/mm of resection at distance and near. The overall success rate was 53% at the final examination after a mean follow-up of 21.9 months. Patients with moderate angles (25 to 45 PD) had a higher success rate than those with 50 PD or greater deviation. Conclusions: Primary bilateral medial rectus resection should be considered as a surgical alternative in childhood exotropia, particularly for moderate and constant deviations.