| 摘要 |
PCT No. PCT/US94/00918 Sec. 371 Date Oct. 5, 1995 Sec. 102(e) Date Oct. 5, 1995 PCT Filed Jan. 25, 1994 PCT Pub. No. WO94/17435 PCT Pub. Date Aug. 4, 1994A multifocal contact lens has diffractive power arising from a series of concentric zones each providing an asymmetric retardation of light across the zone width to direct light predominantly into a required order and sign of diffraction. At least some of the concentric zones are shaped so that the step height varies so that it is different in one region (A) of the lens from that in another region (B), whereby the intensity of light associated with an image observed by diffraction at one order in that region (A) of the lens is greater than the light intensity associated with the same image when observed at the same order through another region (B) of the lens. |
