Horizontal Transposition of the Vertical Rectus Muscles for Cyclotropia

Abstract

We studied the effect of horizontal transposition of the vertical rectus muscles on incyclotropia and excyclotropia in terms of the amount of correction obtained and the stability of the outcome. Preoperative measurements for cyclotropia were compared in 11 patients with measurements during the immediate postoperative period and last follow-up. Excyclotropia was treated with nasal transposition of the inferior rectus muscle and incyclotropia with nasal transposition of the superior rectus muscle, to which we added temporal transposition to the inferior rectus muscle in one patient to enhance the effect. Fusion in all gaze positions was restored in six patients and functional improvement occurred in five. The average effect of horizontal transposition of one vertical rectus muscle for cyclotropia was a correction of 7 degrees in primary position and of 11 degrees in depression. This effect remained stable after a mean follow-up of 17 months, and additional improvement occurred in one patient. One patient developed a hypertropia, eliminated by an additional operation, in the treated eye. For excyclotropia, nasal transposition of the inferior rectus muscle is a viable alternative to lateral and anterior transposition of the anterior portion of the superior oblique tendon. It becomes the procedure of choice when surgery on the superior oblique tendon is precluded, either by the tendon's congenital absence or by previous surgery on the tendon. Nasal transposition of the superior rectus muscle or temporal transposition of the inferior rectus muscle is ideally suited for incyclotropia. No comparably effective operation exists.