Surgery for Esotropia: The Legend of the Dose-Response Curve Re-visited and the Optimal Surgical Strategy.

ObjectiveTo determine clinical predictors of surgical failures following horizontal strabismus surgery for esotropia, in order to estimate the optimal surgical strategy. DesignRetrospective pooled observational case series of published cases. SubjectsPatients having horizontal strabismus surgery for esotropia, published between 1940 and 2025, with known preoperative deviation, surgical approach, and outcome. MethodsClinical data from individual patients having strabismus surgery for esotropia was recorded from published case series, and analyzed using multivariable logistic regression to predict over- and under-correction. Main Outcome MeasureSurgical failure, as determined by reoperation, suture adjustment, or postoperative strabismus of 10 prism diopters or more. ResultsWe abstracted individual patient data for 3518 surgeries from 163 publications. Binocular (as compared with monocular) surgery was associated with fewer under-corrections (odds ratio [OR] 0.75, 95% CI 0.61 to 0.92, p=0.005) and more over-corrections (OR 1.87, 95% CI 1.26 to 2.79, p=0.002, n=3266). Increasing preoperative deviation was associated with more under-corrections (OR 1.06/{degrees}, 95% CI 1.05/{degrees} to 1.07/{degrees}, p<0.0001) and fewer overcorrections (OR 0.97/{degrees}, 95% CI 0.95/{degrees} to 0.99/{degrees}, p=0.001, n=3266). Increasing surgical dose was associated with fewer under-corrections (OR 0.95/mm, 95% CI 0.91/mm to 0.99/mm, p=0.01), and more over-corrections (OR 1.08/mm, 95% CI 1.01/mm to 1.16/mm, p=0.02, n=3266). The failure rate was minimized with a large per-muscle surgical dose. As the preoperative deviation increases, one progresses from unilateral recessions, to unilateral recession-resections, and then bi-medial recessions. Under a range of assumptions, bi-medial recessions of 6 mm are optimal for preoperative deviations of 45 to 50 prism diopters. ConclusionsLarger doses for esotropia surgery do produce a larger response. Most models predicted the lowest failure rates with large recessions or resections, with additional muscles operated for larger preoperative deviations. Thus, the analysis supports the approach of Scobee (1951) over that of Parks (1975). The preferred surgical strategy depends on multiple factors.