An anatomical reevaluation of rectus muscle insertions.

Certain strabismus operations require a thorough knowledge of the anatomy of rectus muscle insertions. Earlier anatomical studies were based on a small sample size and did not use precise microscopic techniques for measurements. To obtain accurate measurements of rectus muscle insertion relationships, 100 consecutive normal adult autopsy eyes were examined with a Vernier caliper and a dissecting microscope for high magnification. Statistical analysis of these data provided a set of normal values for (1) distances from anterior and posterior limbus to rectus muscle insertions, (2) distances between anterior and posterior limbus, (3) length of line ("width") of rectus muscle insertions, and (4) distances between rectus muscle insertions. Although most of the determinations were somewhat similar to older previous studies, statistically they were significantly different. The ophthalmologist can make use of the revised set of figures for rectus muscle insertion relationships in operations such as transposition procedures for A-V patterns and cranial nerve palsies, large recessions, and advancements in reoperations after recessions.