Variation in axial length and anatomical landmarks in strabismic patients.

The authors calculated axial length measurements in 185 consecutive patients undergoing strabismus surgery and found a mean measurement of 21.98 +/- 1.59 mm (range, 18.75-25.37 mm). Although significant correlation between axial length, refractive error, and age was found, wide variation was present, which indicates that age and refractive error could not accurately predict axial length. Based on a formula derived from a geometric model to determine the equator-limbus distance, given the axial length, the authors found that the equator had a mean distance from the limbus of 11.56 +/- 1.75 mm (range, 9.10-13.76 mm). Based on the variability found at surgery for the insertion-limbus distance, the number of millimeters of recession of the medial rectus from the insertion that would have been necessary to place it at the equator ranged between 3.5 and 8.5 mm in this series, and for the lateral rectus, 3.5 mm to 7.0 mm. The number of millimeters necessary to recess the lateral rectus to its point of tangency with the globe ranged between 9.5 and 14.4 mm.