Anterior Transposition of the Inferior Oblique Muscle for Treatment of Hypertropia in Superior Oblique Muscle Palsy

Anterior transposition is one of the most commonly used inferior oblique weakening procedures. It has been known to be effective in the case of dissociated vertical deviation with inferior oblique overaction or hypertropia due to superior oblique palsy. this study was undertaken to determine whether anterior transposition is effective in the correction of vertical deviation and head tilt in 19 patients with hypertropia due to superior oblique palsy. Preoperative average scale of inferior oblique overaction was ＋2.4±0.7mm, and the elimination of overaction was noted in 14 patients(74%). Preoperative prism-cover for hypertropia in primary position averaged 12.7±6.2, and the mean reduction of hypertropia in primary position was about 10. Head tilt was uniformly eliminated in 9 of 12 atients(75%). Therefore, we can expect the reduction of hypertropia about 10 and the elimination of head tilt, using only anterior transposition in hypertropia and inferior oblique overaction due to superior oblique palsy, especially when the amount of vertical deviation is within 13.ope