The study of re-establishment of binocular vision and the impact factors in adults after exotropia surgery

Objective To study the restoration of binocular vision and the factors that impact adults after exotropia surgery. Methods Fifty-four adult patients with exotropia were divided into two groups, based on age of onset: before visual maturity(BVM, <9 years old)or after visual maturity(AVM, ≥9 years old). Binocular vision, both distance and near, was checked before surgery and 6 weeks after surgery with a synoptophore and Yan' s digital stereogram. Results The restoration rate of distance binocular vision was as follows: For grade I binocular vision, the rate was 77% in the AVM group, which was significantly higher than the rate for the BVM group(33%; χ2=10.240, P<0.01). For grade Ⅱ, the rate was the same as for grade I. For grade III, the rate was 47% in the AVM group and was 17% in the BVM group. Differences between the two groups were statistically significant(χ2=5.400, P<0.05). The restoration rate of near binocular vision was 73% in the AVM group, which was significantly higher than that for the BVM group(29%; χ2=10.461, P< 0.01). Logistic analysis showed that the age of onset and the age at the time of surgery are the important factors affecting the restoration of postoperative distance(OR=6.046, P<0.05; OR=0.140, P< 0.01)and near stereopsis(OR=10.825, P<0.05; OR=0.189, P<0.05). The type of exotropia and the degree of the preoperative strabismus had no marked influences on binocular vision. Conclusion Surgical correction of adult exotropia is helpful in the restoration of binocular visual functions and beneficial to obtaining a certain degree of stereopsis. The restoration of distance stereopsis is associated with the age of onset and the age at the time of surgery. The age of onset played a key role in obtaining stereopsis. In order to improve postoperative binocular vision, surgery should be performed as early as possible for adult exotropia patients. Key words: Adult; Exotropia; Binocular vision; Stereoacuity