Comparison between Down Transposition and Slanted Surgery for Bilateral Lateral Rectus Recession in Convergence Insufficiency-Type Exotropia

Abstract

Purpose: We compared bilateral lateral rectus recession with down transposition and slanted bilateral lateral rectus recession as surgical methods for convergence insufficiency-type exotropia.Methods: We included patients who underwent bilateral lateral rectus recession with down transposition or slanted bilateral lateral rectus recession for convergence insufficiency-type exotropia from January 2012 to January 2021 and observed them for more than 1 year. We retrospectively analyzed sex, age, preoperative best-corrected visual acuity, spherical equivalent, axial length, amount of surgery, and deviation angle before surgery and after surgery (immediately, 1 week, 6 months, and 1 year). We also examined surgical success and stereopsis before surgery and after 6 months and 1 year.Results: The down transposition group included 45 patients and the slanted group included 40. The deviation angle of distance, deviation angle of near and the near-distance disparity (NDD) all decreased in the down transposition group and slanted group 1 year after surgery (1.96 ± 8.77 prism diopter [PD] and 4.60 ± 4.99 PD, respectively; 5.53 ± 9.09 PD and 9.03 ± 9.09 PD, respectively; and 3.58 ± 5.26 PD and 4.43 ± 5.32 PD, respectively). Surgical success after 1 year was 55.6% in the down transposition group and 52.5% in the slanted group, and there was no significant difference between the two groups.Conclusions: In convergence insufficiency-type exotropia, both bilateral lateral rectus recession with down transposition and slanted bilateral lateral rectus recession were effective to correct the deviation angle of near, distance, and NDD. Both are suitable primary surgical methods for convergence insufficiency-type exotropia.