Clinical Characteristics and Outcomes after Augmented Medial Rectus Muscle Recession in Patients with Acute Acquired Comitant Esotropia

Purpose: To analyze the clinical characteristics of patients with acute acquired comitant esotropia, evaluate the outcomes of augmented medial rectus muscle recession, and propose indicators for determining the appropriate surgical dosage. Methods: Data of patients with acute acquired esotropia who underwent medial rectus recession between 2016 and 2022 were retrospectively analyzed. The amount of medial rectus muscle recession was 1-2 mm greater than for other types of esotropia. Surgical success was assessed by reference to the angle of deviation and diplopia status 6 months after surgery. We investigated the amount of additional recession required for favorable surgical outcomes, the characteristics of groups that required augmentation, and changes in surgical amount according to the deviation angle. Results: A total of 38 patients were included; the average refractive error was -3.79 ± 3.11 diopters (D). Patient age at the time of surgery was 25.6 ± 18.2 years and the preoperative deviation angle was 38.1 ± 11.5 prism diopters (PD). The amount of medial rectus muscle recession was 6.25 ± 1.4 mm, i.e., 1.2 ± 1.0 mm greater than during other surgeries. The average augmentation was 24.1 ± 18.8%. The motor surgical success rate was 92.1% and the sensory success rate was 97.4%. The required augmentation was 26.9% for those with angles of deviation < 30 PD, 25.5% for patients with angles between 30 and 40 PD, and 20.0% for those with angles > 40 PD. Patients who required augmentation > 25% were older, and the surgical effect was greater as the angle of deviation increased. Conclusions: To ensure successful surgical outcomes of patients with acute acquired comitant esotropia, it is essential to increase the amount of medial rectus recession compared to that during other surgeries; the average augmentation was 24% in this study.