Progressive ophthalmic lens with positive distance power
AssigneeOptische Werke G. Rodenstock
InventorsRudolf Barth, Klaus Wehmeyer
Life of this patent
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Abstract
Disclosed is a progressive ophthamic lens having positive distance portion power, in which at least one surface is designed as a progressive area, and a distance portion (FT) intended for distant vision having practically constant distance portion power and a near portion (NT) intended for hear vision having practically constant near portion power including a progression zone (PZ), in which the surface refractive power increases from the surface refractive power (D.sub.F) present at the distant reference point (B.sub.F) along a curved of plane main meridian (HM) to the surface refractive power (D.sub.N) present at a near reference point (B.sub.N).
Claims10
A progressive opthalmic lens having positive distance portion power, in which at least one surface is designed as a progressive area, and a distance portion (FT) intended for distant vision having practically constant distance portion power and a near portion (NT) intended for near vision having practically constant near portion power including a progression zone (PZ), in which the surface refractive power increases from the surface refractive power (D.sub.F) present at the distant reference point (BN.sub.F) along a curved of plane main meridian (HM) to the surface refractive power (D.sub.N) present at a near reference point (B.sub.N), having the following features:
- in the lower region of the progression zone and in the near portion, the radius of curvature of the intersecting lines of horizontal planes (y=const) with the progressive surface becomes
- larger, if said progressive surface is the convex front surface, respectively
- smaller, if said progressive surface is the concave surface facing the eye,
- at least within a strip extending on both sides of said main meridian (HM) with increasing distance from said main meridian (HM),
- for the reduction of the thickness of said opthalmic lens is provided a vertical prism having a size ranging from approx. 0.25 cm/m to approx. 3.00 cm/m, which has a subjacent base so that the optical axis is moved in the direction of the near portion (NT),
- for the compensation of the oblique light bundle astigmatism said progressive surface has at least in the upper region of the distance portion and in the plower region of the near portion a surface astigmatism, with the following relationships being true for the radius of curvature R.sub.HM of said progressive surface along the main meridian (HM) and the radius of curvature R.sub.sag perpendicular to the main meridian if said progressive surface is
- said front surface:
- ##EQU3## said surface facing the eye:
- ##EQU4## with .vertline.dR.sub.sag /d1.vertline. being the variation of said curvature perpendicular to said main meridian in points on said main meridian and y.sub.BN the y-coordinates of said near reference point.
Dependencies are inferred from the claim text.