[Long-term clinical effects of the bilateral superior oblique tendon suture spacer in the treatment of A-pattern strabismus]

Abstract

Objective: To investigate the long-term clinical efficacy and safety of the bilateral superior oblique tendon suture spacer in treatment of A-pattern strabismus with superior oblique overaction (SOOA). Methods: Retrospective case series study. Twenty-one A-pattern strabismus patients who received the quantitative bilateral superior oblique tendon suture spacer with a complete follow-up from January 2009 to August 2017 were enrolled. Among these patients, 19 were exotropic and 2 were esotropic, including 11 males and 10 females, aged (14±9) years. Patients with unilateral superior oblique overaction, Broun syndrome or Helveston syndrome were excluded. The A-pattern strabismus, objective torsion, function of the superior oblique muscle and binocular vision were examined pre-and post-operatively. Paired t-test was used for normal distribution data, Wilcoxon rank-sum test was used for non-normal distribution data, Spearman rank correlation test and simple linear regression were used to analyze the correlation between the two variables. Results: The follow-up was 12 to 109 months (mean, 26±17 months). Twenty patients showed good alignment in the primary position with a deviation angle less than 10 prism diopter (PD), and 1 patient with esotropia had an angle greater than 15 PD. All the patients had no A pattern after surgery. The average pre-and post-operative A-patterns were (23.81±9.47) PD and (0.90±3.59) PD (t=11.29, P<0.01), respectively, and the average corrected A pattern was (23.52±9.68) PD.The average pre-and post-operative torsion was 3.18°±3.26° and -4.81°±4.13° (t=8.87, P<0.01), espectively, and the average corrected torsion was 7.95°±3.88°. No patient complained of torsional diplopia after surgery. The average amount of pre-and post-operative SOOA was 3.0 (2.0) and 0.0 (1.0) in 42 eyes (Z=-5.78, P<0.01), respectively. Suture extension of the superior oblique tendon was related with the pre-operative SOOA (r=0.47, P<0.01), but was not related with the pre-operative torsion (r=0.02, P=0.88). The linear regression results was suture extension=2.71× the grade of pre-operative SOOA (t=27.93, P<0.01). Conclusions: The bilateral superior oblique tendon suture spacer can improve the A-pattern, objective torsion and SOOA, with no torsional diplopia or V pattern after the long-term follow-up. It is a safe and effective superior oblique muscle weakening procedure. (Chin J Ophthalmol, 2020, 56: 853-858).

Keywords: A-pattern strabismus; Ophthalmologic surgical procedures; Strabismus; Superior oblique; Tendon suture spacer.