Progressive lens

摘要

PCT No. PCT/AU97/00240 Sec. 371 Date Dec. 15, 1998 Sec. 102(e) Date Dec. 15, 1998 PCT Filed Apr. 17, 1997 PCT Pub. No. WO97/40415 PCT Pub. Date Oct. 30, 1997A progressive ophthalmic lens element including a lens surface having upper viewing zone providing good optical quality at a predetermined low surface power over a large area of vision; said predetermined power being determined by the viewer's distance prescription (Rx) the horizontal fitting position normally being determined by the inter pupillary distance of the wearer, and the vertical fitting position normally being determined by the vertical frame midpoint; a lower viewing zone of higher surface power providing an enhanced range of vision for intermediate or lesser viewing distances; and a corridor of relatively low astigmatism extending therebetween; wherein the contours of mean surface power and/or surface astigmatism within the lower viewing zone, upper viewing zone and corridor are generally symmetric about a vertical lens meridian.