Surgical treatment of superior oblique palsy: Predictors of outcome.

Purpose: The purpose of this study was to evaluate the incidence and outcome of surgically treated superior oblique palsy (SOP) and the factors involved in its resolution.

Methods: We performed a retrospective study of 76 patients who underwent surgery for SOP. We recorded data from the physical examination and the number and type of procedures performed. Favorable outcome was defined as resolution of or improvement in torticollis (≤5°) and diplopia in primary position (PP) and downgaze or as vertical deviation (VD) <5 prism diopters (pd) in PP and 10 pd in the oblique diagnostic position.

Results: Mean age was 33.12 years. Congenital SOP was the most frequent type (65.8%). Mean preoperative VD was 15.89 ± 9.94 pd, decreasing to 3.07 ± 4.36 pd after surgery. Associated horizontal deviation was recorded in 51.32% of cases. The mean number of procedures was 1.37 ± 0.62 (range 1-4), with 69.7% of patients requiring only one procedure. The mean number of muscles operated on was 1.96 ± 1.01 (inferior oblique being the most frequent). A greater reduction in VD after surgery was observed in patients with congenital SOP (P = 0.04). Although none of the factors evaluated influenced surgical outcome, amblyopic patients had a greater risk of reoperation (P = 0.04). A favorable outcome was achieved in 75% of cases. Mean follow-up was 37.08 months.

Conclusion: Congenital SOP was twice as frequent as acquired SOP and although surgery was successful in most cases, a greater reduction in VD was obtained in congenital cases. Amblyopia was identified as a risk factor for reoperation.