Rectus muscle position in V-pattern strabismus. A study with coronal computed tomography scanning.

Coronal computerized tomographic (CT) scans were obtained on ten children with previously unoperated V-pattern strabismus and ten control patients to determine the relationship of rectus muscles to the globe. All patients with V-pattern had sufficient overaction of the inferior oblique muscles to warrant bilateral surgical weakening. Control patients had no strabismus or isolated horizontal deviations without A- or V-patterns. Using a horizontal reference line constructed along the anterior cranial fossa, the mean horizontal rectus-muscle axes were found to approximate the expected value of 180 degrees closely. The vertical rectus muscle axes were excyclotorted in both groups. However, there was no significant difference in the mean superior temporal quadrant angles formed by the intersection of the horizontal and vertical rectus muscle axes. Analysis of covariance with age as the covariant demonstrated a significant relationship (P less than 0.01) between age and the superior temporal quadrant angle measured in each eye. Our data suggest that apparent rectus muscle malposition identified by CT scanning is a function of age and cannot be implicated as an important cause of V-pattern strabismus.