Study: Younger patients at greater risk for exotropia after augmented vertical rectus transposition

J Pediatr Ophthalmol Strabismus. 2011;15(4):326-330

Younger age and less restriction on forced duction testing are risk factors for exotropia after augmented vertical rectus transposition, a study found.

Preoperative exotropia in adduction and smaller deviation at near are additional risk factors for exotropia after medial rectus muscle recession following vertical rectus transposition.

"Augmented [vertical rectus transposition] has been proposed as a means by which to not only improve strabismus and torticollis but also to increase abducting rotations. However, in improving abducting rotations, there is a risk of postoperative overcorrection resulting in exotropia," the study authors said.

Investigators set out to assess risk factors for postoperative exotropia after vertical rectus transposition for Duane syndrome.

The retrospective record review included 14 patients with postoperative exotropia and a control group of 37 patients with postoperative esotropia/orthotropia.

Median patient age was 2 years in the study group and 10 years in the comparator group; the between-group difference was statistically significant (P = .04).

Study results showed that of the 14 exotropic patients postoperatively, six patients became exotropic after augmented vertical rectus transposition; 8 patients developed exotropia after undergoing medial rectus recession.

Patients in the study group showed less restriction on intraoperative forced duction than controls. In addition, patients who developed exotropia after medial rectus recession had appreciably less esotropia at near and in adduction than controls who also underwent vertical rectus transposition and medial rectus muscle recession. The between-group differences were statistically significant (P = .005 and P = .02, respectively).

Between-group differences in forced duction testing were statistically significant (P = .03), the authors said.