[Clinical study on binocular vision in intermittent exotropia before and after surgery].

OBJECTIVE: To give a suggestion of the timing of surgery, the change of binocular vision before and after strabismus surgery was studied in intermittent exotropia. METHODS: One hundred and seventy-one patients, with intermittent exotropia, were divided into 2 groups, based on the age of surgery, Group 1: younger than 9 years of age. Group 2: 9 and older. Binocular vision of both distance and near was checked before and after surgery. RESULTS: The rebuilding rate of near binocular vision after surgery was: 40.0% for Group 1, 63.8% for Group 2 (P = 0.002), with same onset age (< 4 years), the regain rate of Group 1 was 53.1%, Group 2 was 23.8% (P = 0.032). The distance postoperative binocular vision, using Synoptophore, were: grade I: Group 1 98.2%, Group 2 81.9% (P = 0.027), grade II: Group 1 96.4%, Group 2 84.5% (P = 0.024), grade III: Group 1 81.8%, Group 2 73.3% (P = 0.844). With logistic test, the recovery of binocular vision postoperatively is correlated with preoperative near binocular vision as well as the age of onset (P < 0.01 for both). CONCLUSIONS: The surgery will substantially help to rebuild the binocular vision of both distance and near. The age of onset has significant impact on both the forming and the rebuilding of binocular vision. Operation should not be delayed if onset is younger than 4 years old. Even if the age of onset is older than 4, which is past the critical period of vision development, operative correction no later than 9 is still highly suggested, which may help to rebuild a normal distance binocular vision.