Length-tension properties of extraocular muscles in patients with esotropia and intermittent exotropia.

Abstract

The purpose of this study was to determine the passive length-tension characteristics of horizontal recti muscles in patients with non-restrictive horizontal strabismus. A system to measure intraoperative continuous-registration passive length-tension curves of detached extraocular muscles was designed. The size of the preoperative deviation and the change in the deviation as a result of surgery was correlated with the passive tension of the medial rectus muscle in patients with acquired esotropia. Patients with infantile esotropia or intermittent exotropia showed no relationship between passive tension and either preoperative deviation or response to surgery. Surgical recession of both the medial and lateral recti muscles produced large changes in the passive tension characteristics of both of these muscles. Medial rectus muscle recession produced larger changes in the passive tension than equal amounts of recession of lateral recti muscles.