Anterior Transposition of the Inferior Oblique Muscle in the Treatment of Unilateral Superior Oblique Palsy

PURPOSE: To determine whether unilateral inferior oblique anterior transposition alone could be an effective procedure for treating superior oblique palsy with inferior oblique overaction. METHODS: The records of 38 patients who underwent unilateral inferior oblique anterior transposition for unilateral superior oblique palsy with inferior oblique overaction were evaluated. A comprehensive ocular examination including best-corrected visual acuity measurements, ductions, versions, and deviations at near and distance, head tilt test, abnormal head position, dilated fundus examination, and Titmus test was performed prior to and after surgery. RESULTS: The mean patient age was 29 years, the mean follow-up was 32 months, the mean preoperative hypertropia in primary position was 14.29 ± 7.7 prism diopters (PD), and the mean inferior oblique overaction was 3.63 ± 0.67. Anterior transposition of the inferior oblique muscle was effective across a wide range of preoperative primary position hypertropia (4 to 35 PD) with a mean reduction in postoperative hypertropia of 12 PD. Inferior oblique overaction was reduced in all patients. No patient demonstrated postoperative primary position hypotropia. Surgery improved stereoacuity nearly two units using the Titmus stereoacuity scale. CONCLUSION: Anterior transposition of the inferior oblique muscle is effective in correcting inferior oblique overaction and primary position hypertropia in the treatment of unilateral superior oblique palsy.