Z-tenotomy of the superior oblique tendon and horizontal rectus muscle surgery for A-pattern horizontal strabismus

Purpose: Few studies have investigated combined surgeries for horizontal deviation and A pattern caused by superior oblique overaction (SOOA). This study presents our experience with combined surgery and examines the effect of the type of strabismus and prior surgery on outcome. Methods: The medical records of patients who underwent combined surgery for horizontal deviation occurring with A-pattern misalignment from 2000 through 2004 were reviewed. The procedure consisted of horizontal extraocular muscle recession or resection with superior oblique Z-tenotomy. The criteria for surgical success were horizontal deviation at primary gaze of ≤10^Δ, A pattern of ≤8^Δ, and SOOA of ≤1.0. Results: The study group included 28 patients with a mean age of 13.4 years. Thirteen (46.4%) had A-pattern esotropia; 15 (53.6%) had A-pattern exotropia. Fifteen (50%) had undergone previous surgery. The success rate for the whole group was 60.7%. There was no statistically significant difference in success rate between patients with esotropia (53.8%) or exotropia (66.7%) (p = 0.48) or between patients in whom the combined procedure was the primary (71.4%) or secondary (50.0%) treatment (p = 0.246). Measurements of horizontal strabismus remained stable throughout follow-up in the esotropia group but were unpredictable in the exotropia group. Conclusions: The success rate of combined horizontal deviation/A-pattern surgery is unaffected by type of horizontal deviation or prior surgery.