Efficacy of superior oblique split tendon lengthening for A-pattern strabismus

Abstract

Objective To describe the results using split tendon superior oblique elongation with horizontal rectus muscle surgery for A-pattern strabismus. Methods Seven patients with A-pattern strabismus who underwent superior oblique split tendon elongation procedure were retrospectively reviewed. The deviation angle was measured in the primary position, and 25° up-gaze and 25° down-gaze positions pre- and postoperatively. The objective torsion was recorded with fundus photography before and after surgery. Superior oblique over-action (SOOA) was graded from +1 to +4. All patients underwent bilateral superior oblique split tendon lengthening with horizontal rectus muscle surgery. A Wilcoxon matched-pairs signed rank test was used to analyze the data. The follow-up time was from 4 to 10 months. Results Postoperatively, 7 patients showed good alignment in the primary position with a deviation angle less than 10 PD. All A-patterns collapsed into less than 10PD. SOOA improved from +2.71 to +0.71. Fundus photography showed 5.17° less intorsion postoperatively. No patient complained of torsional diplopia after surgery. No new vertical deviation was observed in any of the 7 patients after surgery. Conclusion Superior oblique split tendon elongation effectively improves A-pattern and SOOA. Superior oblique split tendon lengthening is a safe and effective superior oblique weakening procedure. Key words: Superior oblique split tendon elongation; A-pattern strabismus; Superior oblique over-action