To assess the difference in the change of postoperative ocular alignment in intermittent exotropia corrected by horizontal muscle transposition or inferior oblique muscle recession together with lateral rectus muscle recession.

A total of 110 patients with intermittent exotropia with a follow-up period of more than 6 months after lateral rectus muscle recession were enrolled in the present study. The patients who received lateral rectus muscle recession only were classified as group 1, patients who received both lateral rectus muscle recession and horizontal muscle vertical transposition in both eyes were classified as group 2, and patients who underwent lateral rectus muscle and inferior oblique muscle recession were classified as group 3. The differences in postoperative ocular alignment among the patient groups were compared.

Among the 3 groups, group 2 demonstrated the smallest amount of esotropic deviation in mean postoperative ocular alignment measured 1 day and 1 month after surgery. There was no significant difference among the groups in the mean postoperative ocular alignment and mean amount of exotropic drift at 6 months. The difference in the amount of postoperative exotropic drift 1 year after surgery among the 3 groups was statistically significant. The largest amount of postoperative exotropic drift was observed in group 1.

In correcting intermittent exotropia, the largest amount of postoperative exotropic drift was observed in patients who received only lateral rectus muscle recession. By contrast, the smallest amount of postoperative exotropic drift was observed in patients who received lateral rectus muscle recession with vertical transposition of the horizontal muscle.