Quantitative descriptors of corneal topography. A clinical study.

Quantitative descriptors of corneal topography determined by computerized algorithm and designed to augment the information derived from topographic maps were evaluated in a clinical study. The surface regularity index, a measure of central corneal optical quality, was highly correlated with best spectacle-corrected visual acuity (rho = 0.80, P less than .001). The relatively low correlation between the surface asymmetry index, a measure of central corneal asymmetry, and best spectacle-corrected visual acuity (rho = 0.62, P less than .005) suggests that corneal symmetry is a lesser but still important determinant of the optical performance of the anterior corneal surface. There was also a high correlation between factors determined from computer-generated orthogonal simulated keratometer values and clinical keratometry values (mean corneal power, total corneal cylinder, and the location of the steepest corneal meridian). The information derived from these algorithms has both clinical and research applications and can be incorporated into computer-assisted topographic analysis systems.