The relationship of rectus muscles to the globe: a study with coronal CT scanning.

Coronal computerized tomographic scans of 25 patients were reviewed in order to determine the normal relationship of rectus muscles to the globe. Using a horizontal reference line constructed along the anterior cranial fossa, the mean horizontal rectus muscle axis was found to be slightly excyclotorted in both eyes, and the mean vertical rectus muscle axis slightly incyclotorted in both eyes. In addition, the mean superior temporal quadrant angle formed by the intersection of the horizontal and vertical rectus muscle axis was significantly greater than the mean superior nasal quadrant angle in the same eye. The presence of large anatomical variations in individual patients may make it difficult to implicate rectus muscle malposition as an important etiology of A- and V-pattern strabismus.