Fig. 4. A, B, and C. Three circles of increasing length of radius. If the diameter of a given arc of the circle is kept constant, the sagittal height will decrease from A to C. (Stein HA, Slatt BJ, Stein R: Fitting Guide for Rigid and Soft Contact Lenses: A Practical Approach, 3rd ed. St. Louis, CV Mosby, 1990)