AIM: To investigate the long-term outcomes after surgery for intermittent exotropia \〖X(T)\〗, constant exotropia with a previously intermittent history and constant exotropia without a previously intermittent history.

METHODS: Totally 137 patients with intermittent exotropia or constant exotropia who had underwent surgery were analyzed retrospectively. They were assigned into three groups: group 1, seventy-four patients with X(T); group 2, thirty-eight constant exotropia patients with a previously intermittent history; group 3, twenty-five constant exotropia patients without a previously intermittent history. The surgical outcomes in the ocular deviation and the recovery of stereoacuity were compared separately among the three groups. The average follow-up time was 2.2 years.

RESULTS: The successful alignment rates were 78%(group 1), 68%(group 2), 64%(group 3), respectively(group 1 vs group 2, P=0.249; group 1 vs group 3, P=0.153; group 2 vs group 3, P=0.716). Fifty-seven patients(77%)in group 1, five patients(13%)in group 2 and one patient(4%)in group 3 achieved binocularity after surgery(group 1 vs group 2, P<0.001; group 1 vs group 3, P<0.001; group 2 vs group 3, P=0.440). The number of patients who achieved gross stereopsis in group 1, group 2 and group 3 were 66(89%), 27(71%), 8(32%)(group 1 vs group 2, P=0.015; group 1 vs group 3, P<0.001; group 2 vs group 3, P=0.002). Twenty-nine patients(56%)in group 1, 5 patients(24%)in group 2, 1 patients(7%)in group 3 achieved distance stereoacuity(group 1 vs group 2, P=0.013; group 1 vs group 3, P=0.001; group 2 vs group 3, P=0.366).

CONCLUSION: Patients with constant exotropia who had a intermittent history have a better surgical result compared with those without a intermittence period in gross stereopsis, but a worse postoperative sensory outcome than patients with X(T)in binocular vision, gross stereopsis, and distant stereoacuity. Constant exotropia patients with a period of X(T)may have missed the optimal timing for treatment, early surgery can optimize the postoperative sensory results.