Evaluation of three superior oblique surgical weakening procedures for A-pattern strabismus

ABSTRACT Purpose: To evaluate three superior oblique surgical weakening procedures for correcting A-pattern strabismus: tenectomy, superior oblique hang-back recession, and that involving the use of superior oblique suture spacers. Methods: The inclusion criteria were A-pattern strabismus ≥10Δ and horizontal deviation ≥10Δ, with no other ocular abnormality and a follow-up period of ≥6 months. The 24 patients (mean age, 16.3 ± 8.1 years; mean postoperative follow-up, 9.63 ± 3.11 months) were randomly divided into three groups of 8 patients each. Sigmascan® Pro 5.0 software was used to measure the degree of torsion pre- and postoperatively. Results: Preoperatively, the mean angles of A-pattern deviation were 19.33Δ° ± 3.53Δ° (tenectomy group), 15.71Δ° ± 1.11Δ° (hang-back recession group), and 14.62Δ° ± 1.18Δ° (suture spacers group); these values did not differ significantly. At the final follow-up examination, the mean angles of A-pattern deviation were 4.67Δ° ± 0.67Δ° (tenectomy group), 6.29Δ° ± 1.48Δ° (hang-back recession group), and 4.38Δ° ± 1.03Δ° (suture spacers group), with no statistically significant difference in the correction in A-pattern strabismus among the three groups. Preoperatively, the mean torsional angles were +5.4° ± 3.9° (tenectomy group), +5.6° ± 4.9° (hang-back recession group), and +6.0° ± 3.3° (suture spacers group); these values did not differ significantly. At the final follow-up examination, the mean torsional angles were + 0.3° ± 5.6° (tenectomy group), +0.5° ± 4.6° (hang-back recession group), and +0.2° ± 5.2° (suture spacers group), with no statistically significant difference in the intorsion correction among the three groups. Conclusion: All three superior oblique weakening procedures were effective for correcting A-pattern strabismus and fundus intorsion.