Correction of higher order aberrations in intraocular lenses

• US 20070268453A1
• Filed: 05/17/2006
• Published: 11/22/2007
• Est. Priority Date: 05/17/2006
• Status: Active Grant

• Current Assignee: Alcon Incorporated
• Original Assignee: Alcon Manufacturing Limited (Alcon Incorporated)
• Inventors: Zhang, Xiaoxiao, Karakelle, Mutlu, Hong, Xin
• Granted Patent: US 7,879,089 B2
• Time in Patent Office: Days
• US Class Current: 351/177
• CPC Class Codes: A61B 3/0025 characterised by electronic signal processing, e.g. eye models
• CPC Class Codes: A61F 2/141 Artificial eyes
• CPC Class Codes: A61F 2/1637 Correcting aberrations caused by inhomogeneities; correcting intrinsic aberrations, e.g. of the cornea, of the surface of the natural lens, aspheric, cylindrical, toric lenses
• CPC Class Codes: A61F 2240/001 Designing or manufacturing processes
• CPC Class Codes: A61F 2240/008 Means for testing implantable prostheses

Abstract

In one aspect, the present invention provides a method of designing an intraocular lens (IOL) to address variations of at least one ocular parameter in a population of patient eyes. The method can include establishing at least one eye model in which the ocular parameter can be varied over a range exhibited by the population. The eye model can be employed to evaluate a plurality of IOL designs in correcting visual acuity for eyes in the patient population. An IOL design that provides a best fit for visual performance over at least a portion of the parameter range can then be selected.

Claims

1. A method of designing an intraocular lens (IOL) to address variations in at least one ocular parameter in a population of patient eyes, comprising

establishing at least one eye model in which the ocular parameter can be varied over a range exhibited by the population,

employing the eye model to evaluate a plurality of IOL designs for visual performance for eyes in the patient population, and

selecting an IOL design that provides a best fit for visual performance over at least a portion of the range exhibited by the population.

2. The method of claim 1, further comprising applying a weighting function to visual performance exhibited by the IOL designs, said function being based on distribution of the ocular parameter in the population.

3. The method of claim 2, wherein said visual performance comprises visual acuity.

4. The method of claim 3, further comprising determining the best fit for visual acuity as an optimal value of a weighted visual acuity among the IOL designs.

5. The method of claim 1, further comprising generating said IOL designs based on varying at least one lens design parameter.

6. The method of claim 1, wherein said ocular parameter comprises ocular axial length.

7. The method of claim 1, wherein said ocular parameter comprises corneal asphericity.

8. The method of claim 1, wherein said ocular parameter comprises corneal radius.

9. The method of claim 1, wherein said ocular parameter comprises ocular anterior chamber depth.

10. The method of claim 3, further comprising determining a modulation transfer function at the retina of the eye model for obtaining the visual acuity exhibited by the IOL designs.

11. A method of designing an intraocular lens (IOL), comprising

generating a human eye model in which at least one ocular biometric parameter can be varied,

evaluating optical performance of a plurality of IOL designs by incorporating the designs in the eye model and varying said ocular parameter over at least a portion of a range exhibited by eyes in a patient population, and

selecting one of the IOL designs that provides a desirable level of performance.

12. The method of claim 11, wherein said ocular parameter comprises any of corneal radius, corneal asphericity, anterior chamber depth or ocular axial length.

13. The method of claim 11, further comprising generating said IOL designs by varying at least one lens design parameter.

14. The method of claim 13, wherein said lens design parameter comprises any of a conic constant of an aspherical lens surface, two conic constants associated with a toric lens surface or an apodization function associated with step heights at zone boundaries of a diffractive pattern disposed on a lens surface.

15. The method of claim 11, wherein the step of evaluating optical performance of an IOL design further comprises employing the eye model to determine an average visual acuity provided by that design over said ocular parameter range.

16. The method of claim 15, further comprising calculating a modulation transfer function at the retina of the eye model for determining said visual acuity.

17. The method of claim 16, further comprising weighting said average visual acuity in accordance with a probability distribution of the ocular parameter exhibited by the patient population.

18. The method of claim 17, further comprising identifying an IOL design that exhibits the largest weighted average visual acuity as providing an optimal performance.

19. The method of claim 11, further comprising utilizing Monte Carlo simulation for varying said ocular parameter.

20. The method of claim 11, further comprising incorporating an estimate of manufacturing tolerance associated with at least one lens characteristic into one or more of said IOL designs.

21. The method of claim 20, wherein said lens characteristic comprises irregularities associated with a lens surface.

22. The method of claim 20, wherein said lens characteristic comprises a radius of a lens surface.

23. The method of claim 20, wherein said lens characteristic comprises an asphericity of a lens surface.

24. The method of claim 20, wherein said lens characteristic comprises lens thickness.

25. A method of providing an intraocular lens (IOL) for implantation in a patient'"'"'s eye characterized by an ocular parameter within a range exhibited by eyes of patients in a population, comprising

providing a plurality of IOLs having variations in at least one lens design parameter, and

selecting one of the IOLs that provides a best fit for visual acuity over at least a portion of the ocular parameter range for implantation in the patient'"'"'s eye.

26. The method of claim 25, further comprising determining visual acuity exhibited by each IOL for a plurality of ocular parameter values within said range.

27. The method of claim 26, further comprising generating a weighted average visual acuity for each IOL based on a probability distribution of the ocular parameter in the population.

28. The method of claim 26, further comprising identifying the best fit for visual acuity as a maximum value of the weighted average visual acuity.

29. The method of claim 25, wherein said ocular parameter comprises corneal radius.

30. The method of claim 25, wherein said ocular parameter comprises corneal asphericity.

31. The method of claim 25, wherein said ocular parameter comprises anterior chamber depth.

32. The method of claim 25, wherein said ocular parameter comprises ocular axial length.

33. The method of claim 25, wherein said ocular parameter comprises a deviation of line of sight from an optical axis of the eye.

34. The method of claim 25, wherein said lens design parameter comprises a conic constant of an aspherical lens surface.

35. The method of claim 25, wherein said lens design parameter comprises two conic constants associated with a toric lens surface.

36. The method of claim 25, wherein said lens design parameter comprises an apodization function associated with step heights at zone boundaries of a diffractive pattern disposed on a lens surface.

37. The method of claim 26, further comprising calculating a modulation transfer function at the retina of a human eye model incorporating an IOL for determining said visual acuity exhibited by that IOL.

38. A method of designing a family of intraocular lenses (IOLs), comprising

establishing at least one eye model in which at least one ocular parameter can be varied over a range exhibited by a population of patient eyes,

employing the eye model to evaluate a plurality of IOL designs for visual performance for eyes in the patient population,

selecting at least two IOL designs one of which provides a best fit for visual performance for one portion of the population and the other provides a best fit for visual performance for another portion of the population.

39. The method of claim 38, wherein said ocular parameter comprises ocular axial length.

40. The method of claim 38, wherein said ocular parameter comprises corneal asphericity

41. The method of claim 38, wherein said ocular parameter comprises corneal radius.

42. The method of claim 38, wherein said ocular parameter comprises anterior chamber depth.

43. The method of claim 38, wherein the step of selecting at least two IOL designs comprises selecting three IOL designs for three portions of the population, wherein said IOL designs exhibit, respectively, a spherical aberration of about −

0.1, about −

0.2 and about −

0.3 microns.

44. A method of modeling visual performance of an ophthalmic lens, comprising

establishing a model eye that incorporates said ophthalmic lens,

determining a modulation transfer function (MTF) at a retinal plane of said model eye,

utilizing at least one MTF value corresponding to a low spatial frequency to evaluate a contrast sensitivity of said model eye.

45. The method of claim 44, wherein said low spatial frequency is less than about 60 lp/mm (˜

18 cycles/degree).

46. The method of claim 45, wherein said low spatial frequency lies in a range of about 5 to about 60 lp/mm (˜

1.5 to 18 cycles/degree).

47. The method of claim 44, further comprising utilizing at least one MTF value corresponding to a high spatial frequency to evaluate visual acuity of said model eye.

48. The method of claim 47, wherein said high spatial frequency is greater than about 60 lp/mm (˜

18 cycles/degree).

49. The method of claim 44, wherein said ophthalmic lens comprises an intraocular lens.

50. The method of claim 48, wherein said high spatial frequency is in a range of about 60 to about 100 lp/mm (˜

18 to 30 cycles/degree).

51. A method of modeling a visual performance of an ophthalmic lens, comprising

establishing a model eye that incorporates the ophthalmic lens,

determining a modulation transfer function (MTF) at a retinal plane of the model eye, and

utilizing at least one MTF value corresponding to a high spatial frequency to evaluate a visual acuity of said model eye.

52. The method of claim 51, wherein said high spatial frequency is greater than about 60 lp/mm (˜

18 cycles/degree).

53. The method of claim 52, wherein said high spatial frequency is in a range of about 60 to about 100 lp/mm (˜

18 to 30 cycles/degree).