Efficacy of isolated inferior oblique anteriorization on large-angle hypertropia associated with unilateral superior oblique palsy

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To evaluate the results of inferior oblique anteriorization for the treatment of large-angle hypertropia secondary to superior oblique palsy and to determine predictors of success and the occurrence of antielevation syndrome. In this prospective study, 25 patients with unilateral congenital and acquired superior oblique palsy who had a primary position hypertropia of at least 25Δ underwent inferior oblique anteriorization in the paretic eye. Postoperative changes in vertical deviation of primary position and contralateral gaze, abnormal head posture, extorsion, associated horizontal deviation, inferior oblique overaction, superior oblique underaction, and elevation in abduction were examined. Surgical success was defined as residual hypertropia in primary position of ≤4Δ at final examination. The mean age of patients at surgery was 19.8±11.9years (range, 4-49). The mean preoperative deviation in the primary position was 27.6Δ ± 3.2Δ; in contralateral gaze, 35.0Δ ± 3.8Δ; these measurements decreased postoperatively to 4.7Δ ± 5.6Δ and 7.0Δ ± 5.5Δ, respectively, after a median follow-up of 8months. The success rate was 72%, with no difference between patients with a preoperative deviation of 25Δ-29Δ and those with deviation of 30Δ-35Δ. In a multivariate logistic regression, preoperative extorsion was negatively related to success (OR=8.01; P=0.03). At the final follow-up, 4 patients (16%) showed antielevation syndrome and were clinically asymptomatic. In unilateral superior oblique palsy, one-muscle surgery, including inferior oblique anteriorization, can be conducted to resolve large-angle hypertropia of >25Δ. Excyotorsion is a risk factor that increases the likelihood of failure.