Surgical outcome of single-staged three horizontal muscles squint surgery for extra-large angle exotropia

To report the surgical outcomes of 24 patients undergoing single-staged three horizontal muscles squint surgery for extra-large angle exotropia.

Prospective case series of 24 consecutive patients with primary exotropia>60 prism diopters (PD) at distant and underwent single-staged three horizontal muscles squint surgery from 2003 to 2006. Surgery consisted of bilateral lateral rectus recession of 9.0 mm for 50 PD exotropic correction. For every 5 PD remaining angle exceeding 50 PD, we additionally performed 1.0 mm of unilateral medial rectus resection. The mean follow-up period was 15.8 months (range 6.0-38.0 months; SD 9.5 months).

The mean age at surgery was 31.2 years old (range 7-78 years old, SD 18.2 years old). The mean distant preoperative deviation was 71.3 PD (range 60-85 PD, SD 7.7 PD). No limitation of eye movement or diplopia was found. The success rate was higher in the intermittent group (88.2%) than the constant group (42.9%) (P=0.02) and in cases with preoperative deviation of <80 PD (84.2%) compared with those with deviation>or=80 PD (40.0%) (P=0.042).

Measurement of preoperative deviation and the surgery for extra-large angle exotropia made management of this condition difficult. Single-staged three horizontal muscles squint surgery can be one of the options. Further researches on management of exotropia of >80 PD are warranted.