Decentered noncorrective lens for eyewear

A method of manufacturing dual lens eyewear, the method comprising the steps of:

• selecting a desired lens shape for dual lens eyewear;
• selecting a desired wrap and rake for the lens in an as worn orientation;
• locating the desired shape on a vertically and horizontally tapered non-glass lens blank having an optical centerline;
• cutting a lens from the lens blank to conform to the desired shape;
• and
• mounting the lens in the eyewear with the desired wrap and rake such that the optical centerline of the lens is maintained in a horizontal plane within about ±2° of parallel to a vertical plane of symmetry in the eyewear and in a vertical plane within about ±3° of parallel to a horizontal component of the wearer's normal line of sight.

A method of providing a lens for optically corrected mounting in nonprescription dual lens eyewear, the method comprising the steps of:

• obtaining a tapered non-glass lens blank having a spherical anterior surface with a base curvature within the range of from about 8 to about 9½, the lens blank having a thickness that is vertically tapered symmetrically on either side of an equatorial line and horizontally tapered on at least one side of an optical centerline passing through the equatorial line at an optical center;
• selecting a desired lens shape for dual lens eyewear, the lens shape having a mechanical center point;
• selecting a desired lens orientation relative to a wearer's normal line of sight from one eye, the orientation including both a degree of horizontal wrap and a degree of vertical rake;
• identifying a position on the lens blank where the desired lens shape cut from that position places the mechanical center point offset horizontally from the optical center of the lens blank and vertically below the equatorial line, said offset by an amount which corresponds to the degree of wrap and the degree of rake to reduce prismatic shift;
• and
• cutting the desired lens shape from the position.

A method of cutting a nonpowered lens from a decentered lens blank, said lens for use in a dual lens eyeglass frame in which the lens will exhibit both wrap and rake and optical correction in an as-worn orientation, comprising the steps of:

• designing a dual lens eyeglass frame at least to the point of determining a desired rake and wrap of each lens relative to a corresponding normal line of sight through each lens in the as-worn orientation, said desired rake and wrap such that an angle of incidence at which the normal line of sight passes through a posterior surface of the lens is greater than about 95°;
• obtaining a decentered, tapered spherical lens blank having an anterior surface with a base curvature of at least about 7½ and an optical centerline passing through the thickest portion of the lens blank;
• selecting a vertical and horizontal position on the lens blank, relative to the optical centerline, for cutting the lens such that the lens cut from the selected position will exhibit substantially the same three dimensional angular orientation with respect to the optical centerline as it will exhibit with respect to the corresponding normal line of sight once mounted in the dual lens eyeglass frame with said desired rake and wrap in the as-worn orientation, wherein the selected vertical position depends upon said desired rake and the selected horizontal position depends upon said desired wrap;
• and
• cutting the lens from said location on the lens blank.

A method of manufacturing dual lens eyewear having wrap and rake with minimal optical distortion in an as-worn orientation, the method comprising:

• designing a dual lens eyeglass, including defining a lens shape, a degree of wrap and a degree of rake in the as-worn orientation for each of a left lens and a right lens;
• providing a plurality of spherical lens blanks, each having a base curvature of at least about 6, a vertically and horizontally tapered thickness and an optical centerline;
• identifying a horizontal position on one of the lens blanks relative to the optical centerline, at which the lens shape will exhibit the defined degree of wrap while minimizing prismatic distortion in the as-worn orientation for each of the left lens and the right lens;
• identifying a vertical position on one of the lens blanks, relative to the optical centerline, at which the lens shape will exhibit the defined degree of rake while minimizing prismatic distortion in the as-worn orientation for each of the left lens and the right lens;
• and
• cutting the lens from the identified horizontal and vertical position for each of the left lens and the right lens.

A method of constructing a dual lens eyeglass having wrap and rake in an as worn orientation, comprising:

• determining a degree of wrap and a degree of rake for the as worn orientation for each of a left lens and a right lens, said degrees of wrap and rake such that an angle of incidence at which the normal line of sight passes through a posterior surface of the lens is greater than about 95°;
• providing an eyeglass frame to support the left and right lenses with the selected degrees of lens wrap and lens rake in an as-worn orientation;
• providing a first lens blank with a thickness asymmetrically tapered in a vertical dimension and asymmetrically tapered in a horizontal dimension;
• cutting a left lens from a position on the first lens blank which is selected to cooperate with the selected degrees of wrap and rake in the as warn orientation;
• providing a second lens blank with a thickness asymmetrically tapered in the vertical dimension and asymmetrically tapered in the horizontal dimension;
• cutting a right lens from a position on the second lens blank which is selected to cooperate with the selected degrees of wrap and rake in the as warn orientation;
• and
• mounting the left and right lenses to the frame with the selected degrees of wrap and rake in the as worn orientations whereby the asymmetric tapered thickness cooperates with the selected degrees of wrap and rake to reduce prismatic shift compared to a non tapered lens and compared to a vertically and horizontally symmetrically tapered lens mounted with said rake and wrap.

A method of manufacturing optically corrected, nonprescription dual lens eyewear, comprising:

• providing an eyeglass frame configured to maintain a left lens in a first predetermined relationship with respect to a wearer's left reference line of sight and a right lens in a second predetermined relationship with respect to the wearer's right reference line of sight, when the eyewear is worn on the head of the wearer, each predetermined relationship including an amount of wrap and an amount of rake;
• choosing a vertically and horizontally tapered left lens thickness with an associated left optical centerline vertically and horizontally aligned with respect to the wearer's left reference line of sight in the first predetermined relationship, to compensate for prismatic distortion relative to a uniformly thick lens having the first predetermined relationship;
• cutting a left lens with the chosen tapered left lens thickness from a location on a first lens blank;
• choosing a vertically and horizontally tapered right lens thickness with an associated right optical centerline vertically and horizontally aligned with respect to the wearer's right reference line of sight in the second predetermined relationship, to compensate for prismatic distortion relative to a uniformly thick lens having the second predetermined relationship;
• and
• a cutting a right lens with the chosen tapered right lens thickness from a location on a second lens blank.

A method of manufacturing nonprescription, dual lens eyewear exhibiting wrap and downward rake, the method comprising the steps of:

• selecting a desired as worn lens orientation relative to a wearer's reference line of sight;
• obtaining a lens which has been cut from a preselected non centered location on a lens blank, which location relates to the desired as worn lens orientation to achieve a desired optical result, the lens blank comprising an inner surface conforming to a first sphere having a first center, and an outer surface conforming to a second sphere having a second center offset from the first center, a vertically and horizontally tapered lens thickness defined between the inner and outer surfaces, and an optical centerline passing through the first and second centers;
• and
• mounting the lens in a frame with rake and wrap such that the optical centerline is oriented with respect to the wearer's reference line of sight to achieve the desired optical result.