Patent ID: 6168271
Filing Date: 2001-01-02
Classification: A61F,G02C

Abstract:
A method of minimizing prismatic shift in dual lens eyewear adapted to position a right and left lens across a wearer's right and left normal lines of sight, respectively, the method comprising the steps of: cutting a right lens out of a first decentered, vertically and horizontally tapered non-glass lens blank having a first optical centerline passing through a first optical center, the right lens having a first mechanical center spaced vertically and horizontally from the first optical center; cutting a left lens out of a second decentered, vertically and horizontally tapered non-glass lens blank having a second optical centerline passing through a second optical center, the left lens having a second mechanical center spaced vertically and horizontally from the second optical center, each of the first and second blanks having a base curvature of at least about 6; and mounting the right lens in an eyewear frame with a rake angle related to the vertical spacing between the first mechanical center and the first optical center and a wrap angle related to the horizontal spacing between the first mechanical center and the first optical center to reduce prismatic shift by the right lens; and mounting the left lens in the eyewear frame with a rake angle related to the vertical spacing between the second mechanical center and the second optical center and a wrap angle related to the horizontal spacing between the second mechanical center and the second optical center to reduce prismatic shift by the left lens.