The efficacy of superior oblique posterior tenectomy in the treatment of A-pattern exotropia without ocular intorsion: A retrospective study

Background Superior oblique weakening is a common method to treat A-pattern strabismus. This study aims to evaluate the surgical results of the bilateral superior oblique posterior tenectomy procedure to treat A-pattern strabismus patients who had bilateral superior oblique overaction without objective ocular intorsion. Methods The records of 18 consecutive patients who underwent surgery of superior oblique posterior tenectomy close to its insertion with superior oblique overaction (SOOA)-associated A-pattern strabismus between September 1, 2015 and August 31, 2018 were retrospectively reviewed. Ocular alignment, objective torsion, A-pattern and ocular motility were assessed. Ocular alignment was measured in the primary position, 25° upgaze, and 25° downgaze using the prism bar cover test, and torsion was measured using fundus photographs. Results A total of 18 patients (mean age: 15 years; 6 female, 12 male) underwent bilateral superior oblique posterior tenectomy and simultaneous horizontal rectus muscle surgery were included. The mean preoperative A-pattern deviation was 15 PD and the mean postoperative A-pattern deviation was 2.25 PD with a mean reduction of 12.75 PD. The mean preoperative superior oblique overaction was 2.28 and the mean postoperative superior oblique overaction was 0.43 with a mean reduction of 1.85. There was no significant correlation between the ocular torsional, vertical alignment change and the superior oblique posterior tenectomy procedure. Conclusions Superior oblique posterior tenectomy surgery selectively improved the A-pattern and superior oblique overaction but not affect the primary position vertical deviation, as well as the ocular torsion. It is an effective procedure to treat the mild to moderate superior oblique overaction associated A pattern strabismus without ocular intorsion.