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EP-4736815-A2 - INTRAOCULAR LENSES HAVING ZONE-BY-ZONE STEP HEIGHT CONTROL

EP4736815A2EP 4736815 A2EP4736815 A2EP 4736815A2EP-4736815-A2

Abstract

A method and system provide an ophthalmic device. The ophthalmic device includes an ophthalmic lens having anterior surface, a posterior surface and at least one diffractive structure including a plurality of zones. The at least one diffractive structure is for at least one of the anterior surface and the posterior surface. Each zone includes at least one echelette having a least one step height. The step height(s) are individually optimized for each zone. To compensate chromatic aberration of eye from distance to a range of vision, a greater than 2π phase step height may be employed and the step height(s) folded by a phase, which is an integer multiple of two multiplied by π. Hence chromatic aberration of eye may be compensated to improve vision from distance to near.

Inventors

  • The designation of the inventor has not yet been filed

Assignees

  • Alcon Inc.

Dates

Publication Date
20260506
Application Date
20171109

Claims (15)

  1. An ophthalmic lens (110) having at least one focal length, the ophthalmic lens comprising: an anterior surface (112); a posterior surface (114); and at least one diffractive structure (130) on at least one of the anterior surface (112) and the posterior surface (114), the at least one diffractive structure (130) providing multiple focal lengths and including a plurality of zones (122, 134, 136, 138, 134', 136', 138'), wherein each zone of the plurality of zones includes at least one echelette (124, 132, 132') having at least one step height, the at least one step height being individually determined for each zone of the plurality of zones; wherein the at least one echelette is configured to provide an optimized phase difference that is between 2π and 4π to include first and second orders as main orders, and wherein the at least one echelette has a first step height that corresponds to a first phase difference of 2π, and a second step height that corresponds to a second phase difference which is the difference between the optimized phase difference and the first phase difference of 2π and is obtained by folding the optimized phase difference by 2π.
  2. The ophthalmic lens of claim 1, wherein the ophthalmic lens is a contact lens or an intraocular lens (IOL).
  3. The ophthalmic lens of claim 1, wherein the each zone (122, 134, 136, 138, 134', 136', 138') of the plurality of zones is individually optimized for a portion of the plurality of focal lengths.
  4. The ophthalmic lens of claim 1, wherein the each zone (122, 134, 136, 138, 134', 136', 138') of the plurality of zones is individually optimized for the plurality of focal lengths.
  5. The ophthalmic lens of claim 1, wherein the at least one step height includes a plurality of step heights.
  6. The ophthalmic lens of claim 1, wherein the each zone (122, 134, 136, 138, 134', 136', 138') of the plurality of zones is individually optimized for one of a plurality of target positions.
  7. The ophthalmic lens of claim 6, wherein each zone (122, 134, 136, 138, 134', 136', 138') of the plurality of zones constructively interferes at a different target position of the plurality of target positions.
  8. The ophthalmic lens of claim 1, wherein the at least one diffractive structure (130) is on the anterior surface (112) of the ophthalmic lens (110).
  9. The ophthalmic lens of claim 1, wherein the at least one diffractive structure (130) is on the posterior surface (114) of the ophthalmic lens (110).
  10. The ophthalmic lens of claim 1, wherein the plurality of zones (122, 134, 136, 138, 134', 136', 138') correspond to different radial distances from an optical axis (116) of the ophthalmic lens (110), each zone forming a circular or annular region extending between a minimum radius and a maximum radius from the optical axis (116).
  11. The ophthalmic lens of claim 1, wherein the optimized phase difference between 2π and 4π is selected to distribute optical energy between the first diffraction order and the second diffraction order.
  12. The ophthalmic lens of claim 1, wherein the optimized phase difference is greater than 2 1 to compensate chromatic aberration across the plurality of focal lengths.
  13. The ophthalmic lens of claim 1, wherein the optimized phase difference is determined for a design wavelength corresponding to visible light.
  14. The ophthalmic lens of claim 1, wherein the at least one echelette (124, 132, 132') comprises a step profile configured as a Fresnel-type diffractive profile.
  15. The ophthalmic lens of claim 1, wherein the plurality of zones (122, 134, 136, 138, 134', 136', 138') comprise concentric annular zones arranged radially about an optical axis (116) of the ophthalmic lens (110).

Description

FIELD The present disclosure relates generally to intraocular lenses and more particularly to intraocular lenses having zone by zone step height control. BACKGROUND Intraocular lenses (IOLs) are implanted in patients' eyes either to replace a patient's lens or to complement the patient's lens. The IOL may be implanted in place of the patient's lens during cataract surgery. Alternatively, an IOL may be implanted in a patient's eye to augment the optical power of the patient's own lens. Some conventional IOLs are single focal length IOLs, while others are multifocal IOLs. Single focal length IOLs have a single focal length or single power. Objects at the focal length from the eye/IOL are in focus, while objects nearer or further away may be out of focus. Although objects are in perfect focus only at the focal length, objects within the depth of focus (within a particular distance of the focal length) are still acceptably in focus for the patient to consider the objects in focus. Multifocal IOLs have at least two focal lengths. For example, a bifocal IOL has two focal lengths for improving focus in two ranges: a distance focus corresponding to a larger focal length and a near focus corresponding to a smaller focal length. Thus, a patient's distance vision and near vision may be improved. Trifocal IOLs have three focuses: a far focus for distance vision, a near focus for near vision and an intermediate focus for intermediate vision. The intermediate focus has an intermediate focal length between that of the near and far focuses. Multifocal IOLs may improve the patient's ability to focus on distant and nearby objects. In order to fabricate a conventional IOL, optical design software is generally employed. The desired focal lengths and locations of zones on the lens surface are provided. Given these inputs, the entire lens is analytically optimized using the optical software. Stated differently, the diffraction structures for multiple zones are simultaneously optimized using analytic tools. As a result, an IOL may be provided. Although useful in addressing optical conditions, IOLs may suffer from various drawbacks such as longitudinal chromatic aberration and/or a limited depth of focus. Different colors of light have different wavelengths and, therefore, different frequencies. As a result, the IOL focuses light of different colors at different distances from the lens. The IOL may be unable to focus light of different colors at the patient's retina. The polychromatic image contrast for the IOL may be adversely affected. In addition, the depth of focus of the IOL may not be as large as desired. The patient's vision for ranges further from the focal length may be adversely affected. Consequently, an extended depth of focus (EDOF) may be desired. Accordingly, what is needed is a system and method for improving IOLs. SUMMARY A method and system provide an ophthalmic device. The ophthalmic device includes an ophthalmic lens having anterior surface, a posterior surface and at least one diffractive structure including a plurality of zones. The at least one diffractive structure is for at least one of the anterior surface and the posterior surface. Each zone includes at least one echelette having a least one step height. The step height(s) are individually provided for each zone. The at least one step height is also folded by a phase, which is an integer multiple of two multiplied by π. The lens may having the diffractive structure(s) described above may have reduced chromatic aberration and greater EDOF. As a result, performance may be improved. BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings in which like reference numerals indicate like features and wherein: FIGS. 1A and 1B depict a plan and side views of an exemplary embodiment of a multifocal ophthalmic device that includes individually optimized zones and phase folding;FIG. 2 depicts an exemplary embodiment of a sag profile for a diffractive structure of a multifocal ophthalmic lens that includes individually optimized zones and phase folding.FIGS. 3A-3B depict exemplary embodiments of the intensity versus focus shift for a multifocal ophthalmic lens that includes individually optimized zones and phase folding;FIG. 4 depicts an exemplary embodiment of sag profile for a diffractive structure of an ophthalmic lens having an extended depth of focus and that includes individually optimized zones and phase folding;FIGS. 5A-5B depict exemplary embodiments of the intensity versus focus shift a lens that includes individually optimized zones and phase folding;FIG. 6 is flow chart depicting an exemplary embodiment of a method for fabricating an ophthalmic device that includes individually optimized zones and phase folding;FIG. 7 depicts an exemplary embodiment of a sag profile for diffractive structu