Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Patent
1998-12-01
2000-11-07
Epps, Georgia
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
G02C 706
Patent
active
06142627&
ABSTRACT:
A progressive ophthalmic lens designed for use in eyeglass frames having a vertical ("B") dimension <36 mm is presented. The lens features a short (nominally 13-14.5 mm) progressive corridor and a novel treatment of the progressive optics that compensates for the distortion effects, i.e., astigmatism, that would otherwise result from the compression of the optics into a smaller than usual area. That includes (1) permitting a small amount of the astigmatic aberration to extend into the peripheral zones of the distance portion above the distance fitting center, with 0.50 D isocurves of surface astigmatism forming an included angle of about 110.degree., (2) defining a circle of 30 mm diameter centered 2 mm vertically below the distance fitting center in which the maximum value of unwanted astigmatism does not exceed the add value of the lens plus 0.25 D, (3) distributing astigmatism so that the isocurves from D.sub.1 to D.sub.2 on upward arcs (3,4) of the 30 mm circle adjacent the reading zone are much more closely spaced than the isocurves from D.sub.1 to D.sub.2 on downward arcs (1,2) of the 30 mm circle from the distance zone (where ##EQU1## where .DELTA.P is the add value of the lens), and (4) establishing a value .rho. of from 2.7-5 for the ratio of the magnitude of the gradient of astigmatism over the combined lengths of arcs 3 and 4 to the magnitude of the gradient of astigmatism over the combined lengths of arcs 1 and 2. Examples of preferred embodiments are presented having continuous and discontinuous meridional power laws.
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"Statement Accompanying Information Disclosure Statement Dated Jul. 13, 1999", including an Affidavit signed by the inventor, Dr. John T. Winthrop Dated May 7, 1999.
Epps Georgia
Schwartz Jordan M.
Sola International Inc.
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