Bilateral posterior tenectomy of the superior oblique muscle for the treatment of A-pattern strabismus

Purpose To evaluate the efficacy of bilateral posterior superior oblique tenectomy for the treatment of A-pattern strabismus due to superior oblique overaction regardless of the magnitude of the pattern. Methods The medical records of patients with A-pattern esotropia or exotropia in the presence of superior oblique overaction who underwent combined horizontal muscle surgery along with bilateral superior oblique posterior 7/8 tenectomy from 2003 to 2013 were retrospectively reviewed. Patients with at least 3 months' follow-up were included. Results A total of 73 patients were included. Of these, 46 had esotropia; 27, exotropia. The preoperative A-pattern deviation for the study population was 19.6 Δ ± 11.4 Δ (range, 10-60), with a final postoperative patten collapse of 18.2 ± 3.6. Superior oblique overaction was 2.3 ± 0.7 preoperatively and 0.3 ± 0.7 postoperatively. Overall, 87.7% of patients had a successful collapse of their pattern to Δ following the initial bilateral superior oblique posterior tenectomy, with an additional 4.1% following a second procedure. Of patients with a pattern deviation of Δ , 87.9% had successful collapse of the pattern following 1 surgery, and 86.7% of patients who had a pattern of ≥25 Δ had successful collapse. Postoperatively, 7 patients demonstrated mild inferior oblique overaction. No surgical complications were noted. Conclusions A uniform dose of bilateral posterior 7/8 tenectomy surgery successfully collapses A-pattern deviations of all magnitudes.