Long-term surgical outcomes of preoperative prism adaptation in patients with partially accommodative esotropia

Background: To determine the long-term surgical outcomes of preoperative prism adaptation test (PAT) in patients with partially accommodative esotropia. Methods: PAT was performed for the remaining esotropia after full correction of hyperopia. Prism adaptation (PA) responders were defined as patients with stable esodeviation between 0 and 8 prism diopters (PD) while developing sensory fusion throughout the prism adaptation period. Surgical success was defined as a deviation within 8 PD of both the far and near deviation angles at the last follow-up examination. Results: Of the 102 patients, 43 (42.2%) were PA responders, and 59 were PA non-responders (57.8%). After a mean follow-up duration of 6 years after surgery, the surgical success rate was significantly higher in PA responders (76.7% vs. 54.2%,p = 0.023). By multivariate analysis, good stereoacuity at near before surgery significantly correlated with successful outcomes after surgery (p = 0.001,beta = 4.466). The risk factors of undercorrection were preoperative esotropia >35 PD (OR 3.067,p = 0.041), and preoperative hyperopia >+5.25 diopters (OR 3.099,p = 0.049). Among undercorrected patients, the annual decrease of esodeviation was significantly greater in PA responders (p = 0.043). Conclusions: PA responders showed a better long-term success rate than in PA nonresponders. Patients with high hyperopia and large esotropia had a higher risk of undercorrection. Undercorrected patients eventually achieved good motor outcome with postoperative prism correction if they were PA responders before surgery.