The Effect of Modified Anterior Transposition of the Inferior Oblique Muscle for Hypertropia in Superior Oblique Muscle Palsy with Inferior Oblique Muscle Overaction.

purpose : The authers studied the effect of modified anterior transposition of the inferior oblique muscle for hypertropia in superior oblique muscle palsy combined inferior oblique muscle overaction. Methods : We retrospectively analysed 19 cases of superor oblique palsy, which were treated by modified inferior oblique muscle anterior transposition from January 1999 to march 2001. Mean follow-up was 14.6 months. The medial portion of inferior oblique muscle was transpositioned to 1mm posterior position of the temporal insertion of inferior rectus muscle and lateral portion of inferior oblique muscle was moved 5mm on imaginary line, which is the line of between temporal insertion of inferior rectus and inferior insertion of lareral rectus muscle, to the direction of inferior insertion of lateral rectus muscle from temporal insertion of inferior rectus muscle, then backward 6mm from that point perpendicularly. Results : The success rates in modified anterior transposition were 94% in under 20 of hypertropia & 89.5% in over +3 of IOOA. Conclusions : Modified anterior transposition is an effective procedure of +3 to +4 inferior oblique muscle overaction and hypertropia in superior oblique muscle palsy as a primary surgery.