Negative power lens with off-axis curvature center
A convergence-reducing lens, wherein a central normal defines a z-axis, and a central region defines an x-y plane, together defining an x-y-z coordinate system, the convergence-reducing lens comprising a distance-vision region with a negative distance-vision optical power, having a distance-vision front surface with a center of distance-vision front curvature, and a distance-vision rear surface with a center of distance-vision rear curvature; and a near-vision region with an optical power within 0.5 D of the distance-vision optical power, having a near-vision front surface with a center of near-vision front curvature, and a near-vision rear surface with a center of near-vision rear curvature; wherein at least one of an x-coordinate of the center of near-vision front curvature is nasal relative to an x-coordinate of the center of distance-vision front curvature, and an x-coordinate of the center of near-vision rear curvature is temporal relative to an x-coordinate of the center of distance-vision rear curvature.
1. A convergence-reducing lens, wherein:
a central normal of the convergence-reducing lens defines a z-axis, and a central region of the convergence-reducing lens defines a tangential, centered x-y plane, together defining an x-y-z coordinate system of the convergence-reducing lens, the convergence-reducing lens comprising
a distance-vision region with a negative distance-vision optical power, having
a distance-vision front surface with a center of distance-vision front curvature, and
a distance-vision rear surface with a center of distance-vision rear curvature; and
a near-vision region with an optical power within 0.5 D of the distance-vision optical power, having
a near-vision front surface with a center of near-vision front curvature, and
a near-vision rear surface with a center of near-vision rear curvature; wherein at least one of
an x-coordinate of the center of near-vision front curvature is nasal relative to an x-coordinate of the center of distance-vision front curvature, and
an x-coordinate of the center of near-vision rear curvature is temporal relative to an x-coordinate of the center of distance-vision rear curvature, wherein
the distance-vision front surface and the distance-vision rear surface at a nasal x-distance from a center of the coordinate system define a distance-vision surface convergence angle by their corresponding tangentials;
the near-vision front surface and the near-vision rear surface at the nasal x-distance from the center of the coordinate system, at a corresponding y height, define a near-vision surface convergence angle by their corresponding tangentials; and
the near-vision surface convergence angle is greater than the distance-vision surface convergence angle.
2. The convergence-reducing lens of claim 1 , wherein:
the convergence-reducing lens is configured so that at least one of
the x-coordinate of the center of near-vision front curvature is nasal relative to the z-axis of the coordinate system, and
the x-coordinate of the center of near-vision rear curvature is temporal relative to the z-axis of the coordinate system.
3. The convergence-reducing lens of claim 1 , wherein:
the near-vision region has an area larger than 5 mm 2 .
4. The convergence-reducing lens of claim 1 , wherein:
the near-vision region has an area larger than 10 mm 2 .
5. The convergence-reducing lens of claim 1 , wherein:
the near-vision optical power matches the distance-vision optical power within 0.25 D.
6. The convergence-reducing lens of claim 1 , wherein:
a majority of the near-vision region is located in a lower-inferior nasal quadrant of the convergence-reducing lens.
7. The convergence-reducing lens of claim 1 , wherein:
the distance-vision region has a distance-vision z-axis; and
the near-vision region has a near-vision z-axis, wherein
the near-vision z-axis is rotated in a nasal direction relative to the distance-vision z-axis.
8. The eye-strain-reducing lens of claim 1 , wherein:
at least one of the distance-vision region and the near-vision region has at least one of an aspheric component, a power-neutral component, a cylinder, a coma, and an astigmatic component.