Horizontal transposition of vertical rectus muscles for treatment of excyclotropia

Background: Horizontal transposition of the vertical rectus muscles has been performed for treatment of excyclotropia associated with congenital absence of the superior oblique, and for residual excyclotropia after the Harada-Ito operation. However, the amount of excyclotropia that can be corrected and whether this technique alters the vertical muscle balance is not well known. We report the surgical results of three patients with pure excyclotropia who underwent unilateral one-half tendon width horizontal transpositions of vertical rectus muscles. Methods: A one-half muscle width temporal transposition of the superior rectus and nasal transposition of the inferior rectus muscles of one eye was performed in three patients with pure excyclotropia and no associated hypertropia. All three had intermittent torsional diplopia before surgery. Results: Postoperatively, excyclotropia decreased significantly in all fields of gaze, with 8 degrees of reduction by synoptophore and 12.3 degrees of reduction by fundus photography on average, There was no associated vertical or horizontal deviation. All three patients reported improvements of cyclofusion. Conclusion: One-half muscle width temporal transposition of the superior rectus and nasal transposition of the inferior rectus muscles was effective in ameliorating excyclotropia and corrected subjective complaints without altering vertical muscle balance.