Factors influencing the result of superior oblique weakening procedures in patients with superior oblique overaction in horizontal strabismus

BACKGROUND: Few studies have evaluated the surgical outcome of superior oblique weakening procedures in patients with superior oblique overaction associated with exotropia or esotropia. This study aimed to evaluate the outcome of superior oblique muscle weakening and the influencing factors in patients with superior oblique overaction. METHODS: The medical charts of 37 patients (55 eyes) with superior oblique overaction associated with esotropia or exotropia who were treated with a superior oblique weakening procedure at the Seoul National University Hospital from January 2010 to June 2017 were retrospectively reviewed. Superior oblique overaction was graded using, a 6-point scale ranging from + 0.5 to + 3, and pre- and postoperative grades were recorded for all patients. RESULTS: The mean age of the patients was 91.81 ± 59.37 months. Superior oblique muscle suture spacer and superior oblique posterior tenectomy were performed for 17 (23 eyes) and 20 (32 eyes) patients, respectively. Surgical success was achieved in 15 (65.2%) eyes in the suture spacer group and 23 (71.9%) eyes in the posterior tenectomy group. Surgical success was achieved for 69.1% (38/55 eyes) of patients. Dissociated vertical deviation exhibited a significant negative association with the surgical success rate (p < 0.001). CONCLUSIONS: There was no significant difference in surgical success rate between the superior oblique posterior tenectomy and superior oblique suture spacer groups in superior oblique overaction associated with horizontal strabismus. Associated dissociated vertical deviation can affect the surgical success of the superior oblique weakening procedure.