Previous studies have shown that the fluorescein pattern, which is a contact lens fitter's chief guide in evaluating the contact lens‐cornea bearing relationship, is altered by changes in both the contact lens base curve and optic zone diameter. On eight corneas we found the base curve required to maintain an alignment fit for lenses of various optic zone diameters. From the results of this study we can conclude that as the optic zone diameter of a contact lens is increased by 0.5 mm. the base curve must be flattened by 0.25 DK to maintain alignment fitting. This is the Harris‐Kubo ratio: ΔBC/ΔOZD = −0.25 DK/0.5 mm.
Harris et al. (Thu,) studied this question.