Multifocal lens having a progressive optical power region and discontinuity
View Patent ↗Embodiments of the present invention relate to a multifocal lens having a mostly spherical power region and a progressive optical power region. Embodiments of the present invention provide for the proper alignment and positioning of each of these regions, the amount of optical power provided by each of the regions, the optical design of the progressive optical power region, and the size and shape of each of the regions. The combination of these design parameters allows for an optical design having less unwanted astigmatism and distortion as well as both a wider channel width and a shorter channel length compared to conventional PALs. Embodiments of the present invention may also provide a new, inventive far-intermediate distance zone and may further provide for increased vertical stability of vision within a zone of the lens.
1. An ophthalmic lens having a fitting point, comprising:
a far distance zone having a far distance optical power;
a mostly spherical power region on a front surface of the lens for providing additive optical power to the far distance optical power for providing an intermediate distance zone of the lens;
a discontinuity, as viewed through the lens, located between the far distance zone and said mostly spherical power region;
a progressive optical power region on a back surface of the lens that overlaps as viewed through the lens at least a portion of said mostly spherical power region for providing additive optical power to said mostly spherical power region, the progressive optical power region and the mostly spherical power region together providing a near distance zone of the lens; and
a plateau of optical power located in a portion of said progressive optical power region for providing vertical stability of vision in said intermediate distance zone,
wherein said mostly spherical power region and said progressive optical power region contribute to a total add power of the lens; and
at least one of wherein:
said plateau of optical power has a vertical length of approximately 1 millimeter to 3 millimeters, or
said plateau of optical power has a vertical length of approximately 2 millimeter to 6 millimeters.
2. The ophthalmic lens of claim 1 , further comprising:
a blend zone for blending the optical power across at least a portion of said discontinuity.
3. The ophthalmic lens of claim 2 , wherein at least a portion of said blend zone has a width of approximately 2.0 millimeters or less.
4. The ophthalmic lens of claim 1 , wherein said intermediate distance zone has an add power that is between approximately 45% and approximately 55% of the near distance add power of the lens.
5. The ophthalmic lens of claim 1 , wherein the top edge of said mostly spherical power region is located between approximately 3 millimeters and approximately 4 millimeters below the fitting point, and wherein said progressive optical power region starts between approximately 4 millimeters and approximately 8 millimeters from the top edge of said mostly spherical power region.
6. The ophthalmic lens of claim 1 , wherein said discontinuity is caused by a step in optical power.
7. The ophthalmic lens of claim 6 , wherein said step in optical power is a step up in optical power of at least approximately +0.12D.
8. The ophthalmic lens of claim 1 , wherein said progressive optical power region comprises a progressive optical power surface, and wherein said progressive optical power surface is generated by one of free-forming, molding, or surface casting.
9. The ophthalmic lens of claim 1 , wherein said mostly spherical power region is generated by one of free forming a surface of the lens, and molding a surface of the lens.
10. An ophthalmic lens having a far distance zone and a fitting point, comprising:
a far distance zone having a far distance optical power;
a mostly spherical power region on a front surface of the lens for providing additive optical power to the far distance optical power for providing an upper far-intermediate distance zone of the lens;
a discontinuity, as viewed through the lens, located between the far distance zone and said mostly spherical power region;
a progressive optical power region on a back surface of the lens that overlaps as viewed through the lens at least a portion of said mostly spherical power region for providing additive optical power to said mostly spherical power region, the progressive optical power region and the mostly spherical power region together providing an intermediate distance zone of the lens and a near distance zone of the lens; and
a plateau of optical power located in a portion of said progressive optical power region for providing vertical stability of vision in said upper far-intermediate distance zone,
wherein said mostly spherical power region and said progressive optical power region contribute to a total add power of the lens, and
at least one of wherein:
said plateau of optical power has a vertical length of approximately 1 millimeter to 3 millimeters, or
said plateau of optical power has a vertical length of approximately 2 millimeter to 6 millimeters.
11. The ophthalmic lens of claim 10 , further comprising:
a blend zone for blending the optical power across at least a portion of said discontinuity.
12. The ophthalmic lens of claim 11 , wherein at least a portion of said blend zone has a width of approximately 2.0 millimeters or less.
13. The ophthalmic lens of claim 10 , wherein said upper far-intermediate distance zone has an add power that is between approximately 20% and approximately 44% of the near distance add power of the lens.
14. The ophthalmic lens of claim 10 , wherein the top edge of said mostly spherical power region is located between approximately 2 millimeters and approximately 5 millimeters below the fitting point, and wherein said progressive optical power region starts between approximately 4 millimeters and approximately 8 millimeters from the top edge of said mostly spherical power region.
15. The ophthalmic lens of claim 10 , wherein said discontinuity is caused by a step in optical power.
16. The ophthalmic lens of claim 15 , wherein said step in optical power is a step up in optical power of at least approximately +0.12D.
17. The ophthalmic lens of claim 10 , wherein the optical power contributed by the progressive optical power region decreases after the near distance zone for providing a lower far-intermediate zone.
18. The ophthalmic lens of claim 10 , wherein said progressive optical power region comprises a progressive optical power surface, and wherein said progressive optical power surface is generated by one of free-forming, molding, or surface casting.
19. The ophthalmic lens of claim 10 , wherein said mostly spherical power region is generated by one of free forming a surface of the lens, and molding a surface of the lens.
20. An ophthalmic lens having a fitting point, comprising:
a far distance zone having a far distance optical power;
a mostly spherical power region on a front surface of the lens for providing additive optical power to the far distance optical power for providing an intermediate distance zone of the lens;
a discontinuity, as viewed through the lens, located between the far distance zone and said mostly spherical power region; and
a progressive optical power region on a back surface of the lens that overlaps as viewed through the lens at least a portion of said mostly spherical power region for providing additive optical power to said mostly spherical power region, the progressive optical power region and the mostly spherical power region together providing a near distance zone of the lens,
wherein said mostly spherical power region and said progressive optical power region contribute to a total add power of the lens, and
wherein the top edge of said mostly spherical power region is located between approximately 3 millimeters and approximately 4 millimeters below the fitting point, and wherein said progressive optical power region starts between approximately 4 millimeters and approximately 8 millimeters from the top edge of said mostly spherical power region.