doi:US6045438 AWilliam D. ShayUSUS6045438 * Jun 4, 1998 Apr 4, 2000 Shay; William D. Axis block assembly for use in making prescription eyeglass lenses
-0.75 and -3.00 and numerous other values. The plus sign in the spherical value designates a positive lenses. The negative sign designates a negative lens. In an eyeglass prescription, spherical value corrects for far or near vision deficiencies. The lab may maintain a stock of lenses that inc...