Evaluation of surgical outcomes and intervention threshold for small-angle acute acquired comitant esotropia

This study aims to evaluate the safety and efficacy of surgical treatment for small-angle (≤ 15 prism diopters [PD]) acute acquired comitant esotropia (AACE), provide preliminary dose-response estimates and explore the surgical thresholds.

25 patients with small-angle AACE(10-15 PD) underwent unilateral medial rectus (MR) recession with or without lateral rectus (LR) resection, with at least 6 months of follow-up. Causal mediation and multivariable linear regression analysis evaluated the surgical dose-response relationship. Linear modeling estimated the minimum horizontal deviation (surgical threshold) in AACE.

The surgical success rate was 96% (24/25). Mean distant deviation decreased to 0.56 ± 2.12 PD postoperatively (P < 0.001). Fine near stereoacuity increased from 4% to 72%, and those achieving fine or moderate distance stereoacuity from 0% to 72% (both P < 0.001). The base-out recovery point at distance mediated 82.6% of the total effect on the surgical dose (P < 0.001), with adjusted dose responses of 3.76 PD/mm (95% CI, 2.35-5.16; P < 0.001) for MR recession and 3.46 PD/mm (95% CI, 2.62-4.30; P < 0.001) for LR resection. Linear modeling indicated that a recovery point of 15 PD corresponded to a predicted horizontal deviation of 9.96 PD, closely aligning with the lowest distant horizontal deviation (10 PD) observed in this study.

Surgery for small-angle AACE is safe and effective. It may serve as a viable option for patients with deviations as small as 10 PD and a base-out recovery point of at least 15 PD at both near and far, pending validation in larger prospective cohorts.