Eyeglass prescriptions have numbers for Sphere, Cylinder, and Axis. The Sphere correction is for nearsightedness or farsightedness. It refers to how much the glasses lenses should be convex or concave. The Cylinder and Axis numbers are for astigmatism. Perfect eyes have round corneas; an eye ...
doi:US6045438 AWilliam D. ShayUSUS6045438 * Jun 4, 1998 Apr 4, 2000 Shay; William D. Axis block assembly for use in making prescription eyeglass lenses