Four zone multifocal lenses
View Patent ↗The present invention provides multifocal lenses containing at least four zones of different refractive power. The zones are positioned such that the wearer is able to use the inferior-most portion of the lens to more clearly, as compared to conventional multifocal lenses, view objects at distances more than 45 cm from the eye.
1. A progressive spectacle lens comprising at least four zones, each of the zones comprising a refractive power that is different from each refractive power of the other zones, said zones comprising:
a near vision zone, and
an intermediate vision zone located inferior to the near vision zone,
wherein the intermediate vision zone comprises a refractive power gradually decreasing from the refractive power of the near vision zone to a minimum refractive power that is greater than about 25% to about 75% of an add power of the lens, and
the at least four zones form a continuous surface.
2. The lens of claim 1 , wherein the intermediate vision zone comprises a minimum refractive power that is greater than about 35% to about 75% of the add power of the lens.
3. The lens of claim 1 , wherein the minimum power is located at the inferior-most portion of the intermediate zone.
4. The lens of claim 1 , wherein the at least four zones further comprise:
another intermediate vision zone located above the near vision zone.
5. The lens of claim 4 , wherein the at least four zones further comprise:
a distance vision zone located in an upper part of the lens above the another intermediate vision zone,
and wherein the near vision zone comprises the add power of the lens with respect to the distance vision zone.
6. The lens of claim 5 , wherein each of the distance vision zone, near vision zone and both intermediate vision zones are located on one surface of the lens.
7. The lens of claim 1 , wherein the intermediate vision zone located inferior to the near vision zone comprises a superior-most border that is about 15 to about 25 mm below a fitting point of the lens.
8. The lens of claim 1 , comprising a front surface and a back surface, each surface comprising at least four zones, each of the zones comprising a refractive power that is different from each refractive power of the other zones.
9. The lens of claim 8 , wherein the front and the back surfaces are misaligned.
10. A method for designing a progressive spectacle lens, comprising providing at least four zones, each of the zones comprising a refractive power that is different from each refractive power of the other zones, said zones comprising:
a near vision zone, and
an intermediate vision zone located inferior to the near vision zone,
wherein the intermediate vision zone comprises a refractive power that is gradually decreasing from the refractive power of the near vision zone to a minimum power that is greater than about 25% to about 75% of an add power of the lens, and
the at least four zones form a continuous surface.
11. The method of claim 10 , wherein the at least four zones further comprise:
another intermediate vision zone located above the near vision zone.
12. The method of claim 11 , wherein the at least four zones further comprise:
a distance vision zone located in an upper part of the lens above the another intermediate vision zone,
and wherein the near vision zone comprises the add power of the lens with respect to the distance vision zone.