Intrastromal Refractive Correction Systems and Methods

Abstract

Devices, systems, and methods for laser eye surgery selectively ablate tissues within the cornea of an eye along one or more target surfaces, so that corneal tissue bordered by the laser incision surface(s) can be mechanically removed. An appropriate tissue-shaping surface can be selected based on the regular refractive error of the eye, and a shape of the target laser surface(s) can be calculated so as to correct irregular refractive errors of the eye, impose desired additional sphero-cylindrical and/or irregular alterations.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates an exemplary laser eye surgery system and method of its use for correcting regular and irregular refractive errors of an eye.

FIG. 1A is a schematic perspective view of a laser-eye surgery system and patient support system, components of which may be modified for use in the system of FIG. 1.

FIG. 2 is a schematic illustration of a data processing computer system for use in the laser eye surgery systems of FIGS. 1 and 1A.

FIG. 3 schematically illustrates a wavefront measurement system for measuring the regular and/or irregular refractive errors of the eye for use with the surgical systems of FIGS. 1 and 1A.

FIG. 4 is a schematic side view of a simplified model of an eye and tissue-shaping surface and body for use in the system of FIG. 1.

FIG. 5 is a schematic illustration of an image taken from along the optical path through the image shaping body of FIG. 4, showing horizontal and rotational alignment offsets between the tissue shaping body and tissues of the eye, as maybe identified using image processing software in the system of FIG. 1.

FIG. 6 is a schematic side view showing engagement between the tissue-shaping surface and cornea, and also shows a tissue incision depth range.

FIG. 7 is a detailed side view of the tissue-engaging surface and corneal tissue conforming thereto from FIG. 6, and shows laser incision of the corneal tissue along a target tissue surface within a limited depth range, such that both the regular and irregular refractive errors of the eye ere mitigated.

FIG. 7A is a schematic side illustration of the tissue-shaping surface and corneal tissue after the incision of the FIG. 7 is complete, and after the tissue between the target tissue surface and tissue-shaping body has been removed.

FIG. 8 schematically illustrates an alternative system and method in which two tissue surfaces are incised by the laser.

FIGS. 8A and 8B schematically illustrates displacement of an epithelial flap, removal of tissue between the target tissue surfaces, and replacement of the flap with effective refractive correction for both regular and irregular refractive errors.

FIG. 8C illustrates embodiments of methods and systems related to those of FIG. 8A, with the irregular refractive error being compensated for using the anterior laser target surface and the posterior laser target surface being planer.

FIG. 8D illustrates an alternative tissue-shaping body having a plurality of tissue-shaping surfaces.

FIG. 9 schematically illustrates some of the optical and structural components of the laser system of FIG. 1.

FIGS. 10A and 10B are top and side views, respectively, of a laser delivery arm of the system of FIG. 1.

FIG. 11 is a flow chart schematically illustrating a method for treating an eye so as to correct regular and irregular refractive errors.

Claims

1. A method for altering refraction of an eye, the eye having a regular refractive error and capable of benefiting from desired irregular refractive alteration, the method comprising: selecting a tissue-shaping surface substantially corresponding to the regular refractive error;engaging the selected tissue-shaping surface against the eye so as to conform the eye to the selected tissue-shaping surface;determining a laser target surface in response to the desired irregular refractive alteration of the eye; andscanning a laser spot through tissue of the engaged eye along the laser target surface so as to mitigate the regular error and effect the desired irregular refractive alteration of the eye.

2. The method of claim 1, wherein the selecting step comprises selecting a shaping body from among a set of alternative shaping bodies, the shaping bodies having tissue-shaping surfaces corresponding to differing regular refractive errors.

3. The method of claim 2, wherein the set of alternative shaping bodies define a series of spherical and cylindrical steps in power therebetween, wherein the selected tissue-shaping surface corresponds with a selected power, the selected power differing from the regular error of the eye by a power difference, the power difference being less than an associated step in power of the shaping bodies, and wherein the laser target surface is also determined so as to compensate for the power difference.

4. The method of claim 3, wherein the steps in power are each less than or equal to two times a maximum power adjustment of the laser target surface,

5. The method of claim 3, wherein the steps in power are less than or equal to 3.0 D.

6. The method of claim 3, further comprising adjusting the laser target surface per a desired presbyopia-mitigation shape.

7. The method of claim 2, wherein each of the set of alternative selectable tissue-shaping surfaces is disposed on a shaping body comprises a laser transmissive material having laser delivery alignment surfaces and a signal source, the signal source configured to generate signals indicative of an associated power and an identifier of that particular body, and further comprising verifying mounting of an appropriate body for the eye and inhibiting re-use of each of the alternative selectable bodies using the signals.

8. The method of claim 1, wherein the regular error of the eye comprises a cylindrical error having an astigmatism axis, and further comprising rotating the tissue-shaping surface into alignment with an astigmatism axis of the eye.

9. The method of claim 1, further comprising checking alignment between the tissue-shaping surface and the eye after engaging the tissue-shaping surface against the eye.

10. The method of claim 9, wherein the alignment is checked by capturing an image of the engaged eye and determining a horizontal offset and cyclotorsional offset between the engaged eye and the tissue-shaping surface, and further comprising, in response to one or both of the offsets exceeding an alignment threshold, displacing the tissue-reshaping surface away from the eye, moving the eye or the tissue-shaping surface to correct alignment, and re-engaging the tissue-shaping surface against the eye.

11. The method of claim 9, further comprising adjusting a location of the target laser surface relative to the tissue-shaping surface and a shape of the target laser surface in response to an alignment offset between the tissue shaping surface and the eye.

12. The method of claim 1, further comprising mechanically excising tissue from between the target laser surface and the tissue-shaping surface so that the eye has enhanced refractive characteristics after re-growth of removed epithelial tissue.

13. The method of claim 1, further comprising scanning the laser spot along another laser target surface so that first and second tissue surfaces are defined by the laser target surfaces, and mechanically excising tissue from between the first and second tissue surfaces so that the eye has enhanced refractive characteristics when the first tissue surface engages the second tissue surface.

14. The method of claim 1, wherein the laser spot comprises a femtosecond laser spot and separates the tissue of the eye along the laser target surface in about 30 seconds or less, and wherein separated tissue bordered by the laser target surface is primarily mechanically removed rather than primarily relying on volumetric photoablative resculpting.

15. A method for customized correction of an eye, the method comprising: measuring a regular refractive error and an irregular refractive error of the eye, the regular refractive error comprising a spherical error and a cylindrical error, the cylindrical error having a cylindrical power and an astigmatism axis;selecting a tissue-shaping body in response to the regular refractive error of the eye from among a set of alternative tissue-shaping bodies having differing associated spherical and cylindrical powers, the selected tissue-shaping body having a selected tissue-shaping surface, a spherical power substantially corresponding to the spherical error of the eye, and a cylindrical power substantially corresponding to the cylindrical error of the eye;aligning a cylindrical axis of the selected tissue-shaping body with the astigmatism axis of the eye;engaging the selected tissue-shaping surface against the eye so as to conform an eye surface to the selected tissue-shaping surface;determining a target laser surface in response to the irregular refractive error of the eye;incising tissue of the eye by scanning a laser spot through the tissue along the laser target surface; andmechanically excising tissue bordered by the laser target surface so as mitigate the regular refractive error and the irregular refractive error of the eye.

16. The method of claim 15, wherein the target laser surface differs from a nominal surface shape by less than a depth threshold, the depth threshold corresponding to a power of about 1.5 diopters or less.

17. A system for altering refraction of an eye, the eye having a regular refractive error and is capable of benefiting from a desired irregular refractive alteration, the system comprising: a set of alternative tissue-shaping bodies having tissue-shaping surfaces and differing regular refractive powers;a tissue incising laser for transmitting a laser beam along an optical path;a support for positioning a selected tissue-shaping body along the optical path, the selected tissue-shaping body selected from among the set;a processor for determining a laser target surface in response to the desired irregular refractive alteration of the eye; andbeam scanning optics coupled to the processor for scanning the beam along the laser target surface to incise tissue from the eye when the eye engages and conforms to the selected tissue-shaping surface such that removal of the incised tissue mitigates the regular errors of the eye and effects the desired irregular alteration.

18. The system of claim 17, wherein the set of alternative shaping bodies define a series of spherical and cylindrical steps in power therebetween.

19. The system of claim 18, wherein the steps in power are each less than or equal to two times a maximum power adjustment of the laser target surface,

20. The system of claim 18, wherein the steps in power are less than or equal to 3.0 D.

21. The system of claim 18, wherein the selected tissue-shaping surface corresponds with a selected power, the selected power differing from the regular error of the eye by a power difference, the power difference being less than an associated step in power of the shaping bodies, and wherein the processor is configured to determine the target laser surface so as to compensate for the power difference.

22. The system of claim 17, wherein the processor is configured to adjust the laser target surface per a desired presbyopia-mitigation shape.

23. The system of claim 17, wherein each of the set of alternative selectable tissue-shaping surfaces is disposed on an associated shaping body, the shaping bodies comprising a material transmissive to the laser beam and having laser delivery alignment surfaces and a signal source, the signal source configured to generate signals indicative of the selected power and an identifier of that particular body, the signals suitable for inhibiting re-use of the alternative selectable bodies.

24. The system of claim 17, wherein the regular error of the eye comprises a cylindrical error having an astigmatism axis, and wherein the support rotatably supports the tissue-shaping surface about the optical path for alignment of the tissue-shaping surface with the astigmatism axis of the eye.

25. The system of claim 17, further comprising an image capture device optically coupled to the optical path for imaging the eye when the eye engages the tissue-shaping surface, the processor coupled to the image capture device and configured to determine alignment between the tissue-shaping surface and the eye after engaging the tissue-shaping surface against the eye.

26. The system of claim 25, wherein the processor is configured to determine a horizontal offset and cyclotorsional offset between the engaged eye and the tissue-shaping surface in response to alignment data from the image capture device, and wherein the support further comprises a displacement stage coupled to the processor for displacing the tissue-reshaping surface away from the eye and re-engaging the tissue engagement surface against the eye in response to one or both of the offsets exceeding an alignment threshold.

27. The system of claim 26, wherein the processor is further configured for adjusting a location of the target laser surface relative to the tissue-shaping surface and a shape of the target laser surface in response to an alignment offset between the tissue shaping surface and the eye.

28. The system of claim 17, wherein the processor is configured to scan the laser spot along another laser target surface so that first and second tissue surfaces are defined by the laser target surfaces, and such that mechanically excising tissue from between the first and second tissue surfaces and engaging the first tissue surface with the second tissue surface enhances refractive characteristics of the eye.

29. The system of claim 17, wherein the laser comprises a femtosecond laser and the processor is configured to separates the tissue of the eye along the laser target surface in about 30 seconds or less.

30. A tissue-shaping body for use with a system for altering refraction of an eye, the eye having a regular refractive error and an irregular refractive error, the system including a support for positioning the body along an optical path from a laser, and beam scanning optics for scanning along a laser target surface to incise tissue of the eye when the eye engages the body such that removal along the incised tissue mitigates the regular and irregular errors of the eye, the body comprising: a material transmissive of light from the laser; anda tissue-shaping surface defined by the material, the tissue-shaping surface having a cylindrical power substantially corresponding to the regular refractive error of the eye.

31. The body of claim 30, further comprising a signal source for transmitting a signal, the signal indicative of the cylindrical power and an identifier of the particular body suitable for inhibiting re-use of the body.

32. The body of claim 31, further comprising a set of alternatively selectable tissue-shaping bodies having differing tissue-shaping surfaces corresponding to differing cylindrical and spherical refractive powers.