LENGTH-TENSION PROPERTIES OF EXTRAOCULAR-MUSCLES IN PATIENTS WITH ESOTROPIA AND INTERMITTENT EXOTROPIA

The purpose of this study was to determine the passive length-tension characteristics of horizontal recti muscles in patients with nonrestri ctive horizontal strabismus. A system to measure intraoperative contin uous-registration passive length-tension curves of detached extraocula r muscles was designed. The size of the preoperative deviation and the change in the deviation as a result of surgery was correlated with th e passive tension of the medial rectus muscle in patients with acquire d esotropia. Patients with infantile esotropia or intermittent exotrop ia showed no relationship between passive tension and either preoperat ive deviation or response to surgery. Surgical recession of both the m edial 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 a mounts of recession of lateral recti muscles.