Intraocular lens for correcting corneal coma

• US 20070093891A1
• Filed: 10/26/2005
• Published: 04/26/2007
• Est. Priority Date: 10/26/2005
• Status: Active Grant

• Current Assignee: Abbott Medical Optics Incorporated (Johnson & Johnson)
• Original Assignee: Abbott Medical Optics Incorporated (Johnson & Johnson)
• Inventors: Artal, Pablo, Piers, Patricia, Tabernero, Juan
• Granted Patent: US 8,801,781 B2
• Time in Patent Office: Days
• US Class Current: 623/6.23
• CPC Class Codes: A61B 3/0025 characterised by electronic signal processing, e.g. eye models
• CPC Class Codes: A61F 2/1613 having special lens configurations, e.g. multipart lenses; having particular optical properties, e.g. pseudo-accommodative lenses, lenses having aberration corrections, diffractive lenses, lenses for variably absorbing electromagnetic radiation, lenses having variable focus

Abstract

When fitting a patient for an intraocular lens, a series of measurements is taken on the patient'"'"'s eye that determines a required lens power. Next, a range of preferred shape factors may be found, which determine the base (i.e., spherical) radii of the two lens surfaces, essentially independent of the lens power. The preferred shape factor adjusts the third-order coma of the lens to largely offset the coma of the cornea, so that the image at the retina has a reduced amount of third-order coma. Once a preferred shape factor is determined, the base radii of curvature of the anterior and posterior surfaces are determined from the shape factor and the lens power by algebraic formulas. Finally, one or more aspheric terms are added to one or both of the surfaces in the lens, so that the spherical aberration of the lens largely offsets the spherical aberration of the cornea.

Claims

1. A method of specifying the anterior surface and the posterior surface of a lens for implantation in an eye of a subject having a cornea, comprising:

performing at least one measurement on the eye;

determining an optical power from the at least one measurement; and

determining an anterior radius and a posterior radius from the optical power, wherein the anterior radius and the posterior radius minimize the coma of the eye;

whereby the coma of the lens offsets the coma of the cornea.

2. The method of claim 1, further comprising:

determining at least one aspheric term for at least one of the anterior surface and the posterior surface;

whereby the anterior surface and the posterior surface are specified by the anterior radius, the posterior radius and the at least one aspheric term.

3. The method of claim 2, wherein the aspheric term determining step is performed by a ray trace, whereby the spherical aberration of the lens offsets the spherical aberration of the cornea.

4. The method of claim 1, the radius determining step further comprising:

determining a coma contribution of the cornea;

determining a coma contribution of the anterior surface;

determining a coma contribution of the posterior surface; and

selecting an anterior radius and a posterior radius of the lens, wherein the coma contributions of the anterior and posterior surfaces offset the coma contribution of the cornea.

5. The method of claim 4, wherein the coma contribution determining steps are performed by a ray trace.

6. The method of claim 4, wherein the coma contribution of the cornea is determined by measuring the coma contributions of a plurality of subjects and taking the average thereof.

7. The method of claim 4, wherein the coma contribution of the cornea is determined by measuring a corneal radius and a corneal conic constant of a plurality of subjects, generally averaging the corneal radii and the corneal conic constants, and determining the coma contribution of the cornea from the average corneal radius and the average cornea conic constant.

8. The method of claim 4, wherein the coma contribution of the cornea is determined by measurement of the coma contribution on a particular patient.

9. The method of claim 1, wherein the optical power is between 0 diopters and 10 diopters, and the shape factor is between −

3 and −

1.6.

10. The method of claim 1, wherein the optical power is between 5 diopters and 15 diopters, and the shape factor is between −

3 and −

1.2.

11. The method of claim 1, wherein the optical power is between 10 diopters and 20 diopters, and the shape factor is between −

1.9 and −

0.8.

12. The method of claim 1, wherein the optical power is between 15 diopters and 25 diopters, and the shape factor is between −

1.5 and −

0.5.

13. The method of claim 1, wherein the optical power is between 20 diopters and 30 diopters, and the shape factor is between −

1.2 and −

0.2.

14. The method of claim 1, wherein the optical power is greater than 30 diopters, and the shape factor is between −

0.7 and 0.

15. A method of specifying the anterior surface and the posterior surface of a lens for implantation in the eye of a patient, comprising:

performing a measurement capable of determining an optical power, P, of the lens;

determining a shape factor, X, from the optical power;

determining an anterior radius, Ra, and a posterior radius, Rp, from the shape factor and the optical power; and

determining at least one aspheric term for at least one of;

the anterior surface and the posterior surface;

whereby the anterior surface and the posterior surface are specified by the anterior radius, the posterior radius and the at least one aspheric term.

16. The method of claim 15, wherein:

the lens has a refractive index, n;

the lens has an incident refractive index, ni;

the lens has an exiting refractive index, ne;

the anterior radius is determined by

Ra=2(n−

ni)/[P(X−

1)]; and

the posterior radius is determined by

Rp=2(n−

ne)/[P(X+1)].

17. A lens having an optical power for implantation in an eye having a cornea, comprising:

an anterior surface having an anterior radius; and

a posterior surface having a posterior radius;

wherein the anterior radius and the posterior radius determine the optical power; and

wherein the anterior radius and the posterior radius are selected to minimize coma of the eye for the value of optical power;

whereby the coma of the lens offsets the coma of the cornea.

18. A lens having an optical power and a shape factor for implantation in an eye having a cornea, comprising:

an anterior surface having an anterior radius, Ra; and

a posterior surface having a posterior radius, Rp;

wherein the anterior radius and the posterior radius determine the optical power, P, and the shape factor, X; and

wherein the shape factor minimizes the coma of the eye for the value of optical power;

whereby the coma of the lens offsets the coma of the cornea.

19. The lens of claim 18, wherein the shape factor is determined by:

X=(Rp+Ra)/(Rp−

Ra).

20. The lens of claim 18, wherein:

the lens has a refractive index, n;

the lens has an incident refractive index, ni;

the lens has an exiting refractive index, ne;

the lens has a thickness T; and

the optical power is determined by

P=[(n−

ni)/Ra]+[(ne−

n)/Rp]−

[T/n]×

[(n−

ni)/Ra]×

[(ne−

n)/Rp].

21. An intraocular lens having an optical power and a shape factor for implantation in an eye having a cornea, comprising:

an anterior surface having an anterior radius, Ra; and

a posterior surface having a posterior radius, Rp;

wherein the anterior radius and the posterior radius determine the optical power and the shape factor; and

wherein the shape factor is less than −

1.

22. The intraocular lens of claim 21, wherein the optical power is less than 20 diopters.

23. The intraocular lens of claim 22, wherein the optical power is less than 15 diopters.

24. The lens of claim 21, wherein:

the lens has a refractive index, n;

the lens has an incident refractive index, ni;

the lens has an exiting refractive index, ne;

the lens has a thickness T; and

the optical power is determined by

P=[(n−

ni)/Ra]+[(ne−

n)/Rp]−

[T/n]×

[(n−

ni)/Ra]×

[(ne−

n)/Rp].

25. The lens of claim 21, wherein the shape factor minimizes the coma of the eye for the value of optical power;

whereby the coma of the lens offsets the coma of the cornea.