Apodized aspheric diffractive lenses

• US 20060116764A1
• Filed: 12/01/2004
• Published: 06/01/2006
• Est. Priority Date: 12/01/2004
• Status: Abandoned Application

• Current Assignee: Alcon Incorporated
• Original Assignee: Alcon Incorporated
• Inventors: Simpson, Michael J.
• Application Number:
  US11/000,770
• Publication Number:
  US 20060116764A1
• Time in Patent Office: Days
• US Class Current: 623/6.230
• CPC Class Codes: A61F 2/1618 Multifocal lenses
• CPC Class Codes: A61F 2/164 Aspheric lenses
• CPC Class Codes: A61F 2/1654 Diffractive lenses
• CPC Class Codes: G02C 2202/20 Diffractive and Fresnel lenses or lens portions

Abstract

Aspheric diffractive lenses are disclosed for ophthalmic applications. For example, multifocal intraocular lens (IOLs) are disclosed that include an optic having an anterior surface and a posterior surface, at least one of which surfaces includes an aspherical base profile on a portion of which a plurality of diffractive zones are disposed so as to generate a far focus and a near focus. The aspherical base profile enhances image contrast at the far focus of the lens relative to that obtained by a substantially identical IOL in which the respective base profile is spherical.

Claims

1. An apodized diffractive IOL, comprising

an optic having an aspherical base curve, and

a plurality of annular diffractive zones superimposed on at least a portion of said base curve so as to generate a far focus and near focus,

said aspherical base curve enhancing image contrast at a far focus of said optic relative to a substantially identical IOL in which said base curve is spherical.

2. The IOL of claim 1, wherein an optical system comprising said IOL and a patient'"'"'s eye in which said IOL is implanted exhibits a modulation transfer function (MTF) greater than about 0.2 as calculated in a model eye at a spatial frequency of about 50 lp/mm, a wavelength of about 550 nm and a pupil size of about 4.5 mm.

3. The IOL of claim 2, wherein said MTF is in a range of about 0.2 to about 0.5.

4. The IOL of claim 1, wherein an optical system comprising said IOL and a patient'"'"'s eye in which said IOL is implanted exhibits a modulation transfer function (MTF) greater than about 0.1 as calculated in a model eye at a spatial frequency of about 100 lp/mm, a wavelength of about 550 nm and a pupil size of about 4.5 mm.

5. The IOL of claim 1, wherein said diffractive zones are disposed within an apodization zone of a lens surface surrounded by a portion of the lens surface substantially devoid of diffractive structures.

6. The IOL of claim 5, wherein said diffractive zones are separated from one another by a plurality of steps located at zone boundaries and having substantially uniform heights.

7. The IOL of claim 5, wherein each diffractive zone is separated from a neighboring zone by a step having a height that progressively decreases as a function of distance from a central axis of said optic,

8. The IOL of claim 1, wherein said aspherical base curve is characterized by the following relation:

$z=\frac{{\mathrm{cR}}^2}{1+\sqrt{1-\left(1+\mathrm{cc}\right)<br><br>c^2<br><br>R^2}}+{\mathrm{adR}}^4+{\mathrm{aeR}}^6,$

wherein

z denotes a sag of the surface parallel to an axis (z), e.g., the optical axis, perpendicular to the surface,

c denotes a curvature at the vertex of the surface,

cc denotes a conic coefficient,

R denotes a radial position on the surface,

ad denotes a fourth order deformation coefficient, and

ae denotes a sixth order deformation coefficient.

9. The IOL of claim 1, wherein said optic is formed of any of acrylic, silicone, or hydrogel polymeric material.

10. A diffractive IOL, comprising

an optic having an anterior surface and a posterior surface,

at least one of said surfaces comprising:

an aspherical base profile,

a plurality of diffractive zones superimposed on a portion of said base profile, each zone being disposed at a selected radius from an optical axis of said optic and being separated from an adjacent zone by a step,

a peripheral region surrounding said diffractive zones,

wherein said diffractive zones generate a far focus and a near focus and said aspherical profile enhances image contrast at a focus of said optic.

11. The IOL of claim 10, wherein the steps separating the diffractive zones have substantially uniform heights.

12. The IOL of claim 10, wherein the steps separating the diffractive zones have non-uniform heights.

13. The IOL of claim 10, wherein said non-uniform heights exhibit a progressive decrease as the distances of the steps from the optical axis increase.

14. The IOL of claim 10, wherein said diffractive zones comprise concentric annular diffractive elements disposed about the optical axis.

15. The IOL of claim 10, wherein an optical system comprising said IOL and a patient'"'"'s eye in which the IOL is implanted exhibit a modulation transfer function (MTF) greater than about 0.2 as calculated in a model eye at a spatial frequency of about 100 lp/mm and a wavelength of about 550 nm for a pupil diameter of about 4 mm.

16. The IOL of claim 15, wherein said MTF is greater than about 0.3.

17. The IOL of claim 15, wherein said MTF is greater than about 0.4.

18. The IOL of claim 15, wherein said MTF is in a range of about 0.2 to about 0.5.

19. A diffractive IOL, comprising:

an optic formed of a biocompatible polymeric material and having a posterior surface and an anterior surface, said optic providing a near focus and a far focus,

at least one of said surfaces being characterized by a base curve and plurality of diffractive zones disposed as annular concentric diffractive elements about an optical axis, each diffractive element having a height a relative to the base curve that progressively decreases as a distance of the diffractive element from the optical axis increases,

wherein said base curve exhibits an aspherical profile for enhancing image contrast at said far focus for pupil diameters in a range of about 4 to about 5 mm relative to a substantially identical IOL in which said base curve is spherical.

20. The IOL of claim 19, wherein said aspherical base curve is characterized by a conic constant in a range of about −

0.2 to about −

50.

21. An apodized diffractive ophthalmic lens, comprising

an optic having an anterior surface and a posterior surface,

at least one of said surfaces having an aspherical base profile and a plurality of annular diffractive zones disposed on said base profile for generating a near focus and a far focus,

wherein said aspherical profile enhances image contrast at said far focus relative to that obtained by a substantially identical lens in which a respective base profile is spherical.

22. The ophthalmic lens of claim 21, wherein said lens comprises an intraocular lens (IOL).

23. The ophthalmic lens of claim 21, wherein said lens comprises a contact lens.

24. A method of calculating a modulation transfer function (MTF) for an apodized diffractive lens having a plurality of annular diffractive structures disposed at selected radial distances from an optical axis of the lens, comprising

determining an apodization function indicative of diffraction efficiencies at a plurality of radial locations from the optical axis for directing light into a selected diffraction order of the lens,

integrating said apodization function over a selected aperture to determine a fraction of light energy diffractive into said diffraction order, and

scaling a preliminary MTF calculated by assuming said IOL lacks said diffractive structures in accordance with said integrated apodization function to generate the desired MTF.

25. An apodized diffractive lens, comprising

an optic having an anterior surface and a posterior surface, said anterior surface having a plurality of diffractive structures within an apodization zone thereof,

wherein at least of one said anterior or posterior surfaces has a toric shape with two different optical power values along two orthogonal directions along the surface and exhibiting an aspherical profile along at least one of said surface directions.