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Progressive multifocal ophthalmic lenses

  • US 4,580,883 A
  • Filed: 12/03/1981
  • Issued: 04/08/1986
  • Est. Priority Date: 12/05/1980
  • Status: Expired due to Term
First Claim
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1. A progressively varying focal power ophthalmic lens comprising:

  • a refractive surface divided into a far vision viewing zone, an intermediate vision viewing zone and a near vision viewing zone,a substantially vertical principal meridian curve,the far vision viewing zone having an optical center on the principal meridian curve and the near vision viewing zone having an optical center on the principal meridian curve,the curvature of the refractive surface changing between the optical center of the far vision viewing zone and the optical center of the near vision viewing zone in accordance with a prescribed law,the refractive surface being divided into the far vision viewing zone and the intermediate vision viewing zone by a first curve C1 which meets the principal meridian curve at the optical center of the far vision viewing zone, and divided into the intermediate vision zone and the near vision viewing zone by a second curve C2 which meets the principal meridian curve at the optical center of the near vision viewing zone,the refractive surface of the lens further comprising a refractive surface wherein an angle formed by a normal line to the surface from each point on an intersection of an arbitrary plane in parallel with the plane including the principal meridian curve of the refractive surface of the lens and a plane including the principal meridian curve changes in accordance with the same law as that of the curvature of the refractive surface in the intermediate viewing zone between the optical center of the far vision viewing zone and the near vision viewing zone on said principal meridian curve.

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