[Clinical features and surgical treatment of A-pattern exotropia].

Objective: To investigate the clinical features of A-pattern exotropia and to evaluate the efficacy of surgical treatment for the correction of A-pattern exotropia (A-XT).

Methods: Pre- and post-operative eye position, superior oblique muscle function, clinical features and binocular function were examined and analyzed in 32 patients with A-pattern exotropia.

Results: Overaction of the superior oblique (SO) (31/32) and insufficiency of medial rectus muscle (20/32) were commonly seen in the group of patients. The tenectomy of the SO and the resection of the medial rectus muscle were effective in most of A-pattern exotropia. 87.5% (28/35) of A-pattern exotropia in our study were successfully corrected. Four cases got binocular function after surgery.

Conclusions: Based on the clinical features and the effects of surgical treatment, we conclude that the superior oblique muscle overaction and medial rectus muscle insufficiency are the primary factors in the etiology of A-pattern exotropia that is the most common form of A-V syndrome. Weakening the overaction of superior oblique muscle combined with the correction of exotropia is an effective way to correct A-pattern exotropia.