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Multifocal lens

  • US 4,955,712 A
  • Filed: 07/18/1989
  • Issued: 09/11/1990
  • Est. Priority Date: 08/17/1984
  • Status: Expired due to Fees
First Claim
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1. A multifocal ophthalmological lens comprising a front surface facing away from the eye and a rear surface facing toward the eye, the lens having a main portion designed for distance vision and an added portion constituting a near segment designed for near vision, at least one surface of the added portion being composed of a progressive zone having at least one progressive surface in which the refractive power increases, the main portion and the near segment are separated by transition lines, on which transition lines the surface is not twice continuously differentiable, the lens having a main meridian and further comprising the following features:

  • the refractive power of the main portion being constant except for possible aspheric corrections of peripheral abberations, andthe progressive surface of the added portion being formed in such manner that, for the progressive surface in which the refractive power increases, the radius of curvature of the intersecting lines of planes orthogonal to the main meridian in the entire portion of the surfacedecreases, with increasing distance from the main meridian at least in a region surrounding the main meridian, if the progressive surface is the front surface of the lens, orincreases, with increasing distance from the main meridian at least in a region surrounding the main meridian, if the progressive surface is the rear surface of the lens.

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