Anterior and nasal transposition of the inferior oblique muscles in patients with missing superior oblique tendons.

INTRODUCTION: Patients with missing superior oblique (SO) tendons present with overelevation/underdepression in adduction. Unilateral cases often exhibit abnormal head postures, whereas in bilateral cases, there may be a marked V-pattern with upgaze exotropia. These patients may have craniosynostosis. METHODS: Nine children with unilateral (n = 2) or bilateral (n = 7) absent SO tendons underwent anterior and nasal transposition of the inferior oblique (IO) muscles, some in combination with horizontal rectus recession for horizontal strabismus. They were evaluated 6 to 46 months postoperatively for alignment and oculomotor examination. Cyclodeviations were not evaluated in most children. RESULTS: Postoperatively, all patients improved. Both unilateral cases were orthotropic with no abnormal head posture. In the bilateral cases, vertical deviation in adduction and exotropia in upgaze had largely cleared, although some symptoms remained, most notably vertical deviation in side gaze (3 patients) and V-pattern esotropia in downgaze (2 patients). A patient missing both SO tendons as well as the left superior rectus muscle, who had the anterior and nasal transposition on the right side only, remained with 25(Delta) left hypotropia. CONCLUSIONS: Anterior and nasal transposition of the IO muscle reduces overelevation in adduction and helps eliminate or reduce divergence of the eyes in upgaze, but esodeviation may persist in downgaze. This procedure was most effective in unilateral absence of the SO tendon. It is likely to benefit patients with severe congenital fourth nerve palsy in which standard IO muscle weakening procedures have been ineffective.