A study to determine: should conventional amounts of eye muscle surgery for horizontal binocular deviations be changed when oblique muscle weakening procedures are simultaneously performed?

Purpose: To investigate the final surgical outcome in horizontal strabismus correction, measured in primary position of gaze, in two situations: 1. When surgery was performed only on the horizontal rectus muscles; and 2. When inferior or superior oblique muscle weakening procedures were simultaneously performed.

Methods: Two hundred thirty cases were analyzed retrospectively: 172 esotropias (110 without oblique overaction; 23 with inferior oblique overaction; and 39 with superior oblique overaction), and 58 exotropias (25 without oblique overaction; 19 with inferior oblique overaction; and 14 with superior oblique overaction). Initial and final deviations, as well as the amount of correction achieved, was compared in six groups.

Results: No differences in outcomes and final results were found between any of the major or minor groups of patients.

Conclusions: Oblique muscle weakening, in combination with horizontal muscle strabismus surgery did not affect the final results of the horizonal surgery in primary position. This study did suggest that there might not be a need for increasing or decreasing amounts of surgery on the horizontal rectus muscles to correct eso- or exotropia when oblique weakening procedures are included.