Laser eye surgery system using wavefront sensor analysis to control digital micromirror device (DMD) mirror patterns

• US 6,394,999 B1
• Filed: 03/13/2000
• Issued: 05/28/2002
• Est. Priority Date: 03/13/2000
• Status: Expired due to Fees

• Current Assignee: Memphis Eye & Cataract Associates Ambulatory Surgery Center
• Original Assignee: Memphis Eye & Cataract Associates Ambulatory Surgery Center
• Inventors: Freeman, James F., Williams, Roy E., Freeman, Jerre M.
• Primary Examiner(s): Dvorak, Linda C. M.
• Assistant Examiner(s): FARAH, AHMED M
• Application Number:
  US09/524,312
• Time in Patent Office: 806 Days
• Field of Search: 606/4-6,10-13 356/2,4.09,24,27 128/898 351/212
• US Class Current: 606/5
• CPC Class Codes: A61F 2009/00846 Eyetracking
• CPC Class Codes: A61F 2009/00872 Cornea
• CPC Class Codes: A61F 2009/0088 based on wavefront
• CPC Class Codes: A61F 2009/00882 based on topography
• CPC Class Codes: A61F 9/00806 Correction of higher orders
• CPC Class Codes: A61F 9/00817 Beam shaping with masks

Abstract

A system and method for performing corneal ablation or reshaping with a laser in order to correct aberrations in the optical system of the eye utilizes a wavefront sensor which defines a wavefront correction for the eye and then, based upon that defined wavefront correction, drives a digital micromirror device (DMD) which modulates a laser beam to the eye to perform the correction. As the DMD is a 2-D array of individually controlled mirrors, and the wavefront sensor analysis can provide a sequence of two dimensional arrays of values which together define the wavefront correction for the eye, the combination of the two produces a method for correcting the corneal surface. The system may be operated in either of two manners to achieve optimum refractive corrections: (1) off-line measurement of the eye optical system via the wavefront sensor followed by DMD-based laser refractive surgery, or (2) real-time measurement of the eye optical system via the wavefront sensor which directs a DMD-based laser refractive surgery system.

Claims

1. A laser surgery system for reshaping the corneal surface of the eye, said system comprising:

a) a computer system adapted to define a three-dimensional correction for the eye based on wavefront sensor analysis data of the eye;

b) means for creating a sequence of two-dimensional patterns from said three dimensional correction;

c) a laser coupled to said computer system and adapted to reshape a portion of a cornea of the eye; and

d) a digital micromirror device (DMD) having a plurality of mirrors, said mirrors of said DMD being driven into said sequence of two dimensional patterns such that a laser beam produced by said laser is modulated to reshape the cornea of the eye according to said correction.

2. A system according to claim 1, wherein:

said wavefront analysis data is a three dimensional analysis of the optical system of the eye.

3. A system according to claim 1, further comprising:

d) a wavefront sensor analysis system which generates said wavefront sensor analysis data, said wavefront sensor analysis system being coupled to said computer system.

4. A system according to claim 3, wherein:

said laser is adapted to produce a laser light beam at a first wavelength, said wavefront sensor analysis system is adapted to use a light beam at a second wavelength different than said first wavelength, and said laser surgery system further includes a beamsplitter adapted to split said light at said first wavelength from said light said second wavelength.

5. A system according to claim 1, further comprising:

d) a wavefront sensor analysis system which generates said wavefront sensor analysis data; and

e) means for providing said wavefront analysis data to said computer system, said means for providing comprising one of a removable storage media, a computer network, a data cable, and a wireless transmitter.

6. A system according to claim 1, wherein:

each of said patterns of said sequence of two dimensional patterns represents tissue to be reshaped or removed from the cornea at different layers of the cornea.

7. A system according to claim 6, wherein:

each pattern in said sequence of two dimensional patterns is unique.

8. A system according to claim 1, further comprising:

d) an eye tracking system adapted to track movement of the eye, wherein said computer system defines a sequence of patterns representing locations at which a laser beam produced by said laser is to be directed to reshape or remove tissue from the cornea, and is adapted to drive said mirrors of DMD into said sequence of patterns, and

wherein said eye tracking system provides feedback to said computer system to offset said patterns on said plurality of mirrors of said DMD according to movement of the eye.

9. A system according to claim 1, wherein:

said laser is one of an excimer laser and a YAG laser.

10. A system according to claim 1, wherein:

said laser is one of a pulsed beam laser and a continuous wave laser.

11. A method for correcting the shape of a cornea of an eye to improve vision, said method comprising:

a) providing a laser surgery system adapted to perform corrective surgery on the cornea of the eye, said laser surgery system including a laser and a digital micromirror device (DMD) including a plurality of mirrors adapted to modulate a laser beam produced by said laser, said DMD positionable between said laser and the eye;

b) providing wavefront analysis data representing information about the eye;

c) utilizing said wavefront analysis data to define a sequence of patterns for said laser beam, each of said patterns representing a particular layer of the cornea to be corrected;

d) directing said mirrors of said DMD to form a first of said sequence of patterns;

e) firing said laser at said DMD such that said laser beam is directed by said DMD to contact said cornea in said first of said sequence of patterns; and

f) repeating said directing said mirrors of said DMD and firing said laser for a next of said sequence of patterns.

12. A method according to claim 11, further comprising:

repeating said directing said mirrors and said firing for all patterns in said sequence of patterns.

13. A method according to claim 11, further comprising:

prior to firing said laser a first time, exposing a corneal stroma of the cornea.

14. A method according to claim 11, wherein:

said exposing includes one of

i) cutting a flap across the corneal stroma and bending the flap back to expose the corneal stroma, and

ii) removing an epithelial layer of the cornea.

15. A method according to claim 11, further comprising:

after firing said laser for each of said remaining sequence of patterns, covering said corneal stroma.

16. A method according to claim 11, wherein:

prior to utilizing said wavefront analysis data, adjusting said wavefront analysis data.

17. A method according to claim 11, further comprising:

after said directing and said firing, repeating said providing and utilizing in order to modify said sequence of patterns.

18. A method according to claim 11, wherein:

said wavefront analysis includes registration information facilitating relating said wavefront analysis to a moving eye.

19. A method according t o claim 11, wherein:

said directing said mirrors of said DMD to form a first of said sequence of patterns includes adjusting said mirrors according to movement of the eye.

20. A method according to claim 11, wherein:

said firing includes scanning said laser beam across said DMD.

21. A method for correcting the shape of a cornea of an eye to improve vision, said method comprising:

a) providing a laser surgery system adapted to perform corrective surgery on the cornea of the eye, said laser surgery system including a laser and a digital micromirror device (DMD) including a plurality of mirrors adapted to modulate a laser beam produced by said laser, said DMD positionable between said laser and the eye;

b) providing wavefront analysis data representing information about the eye;

c) utilizing said wavefront analysis data to define a sequence of patterns for said laser beam, each of said patterns representing a particular layer of the cornea to be corrected;

d) directing said mirrors of said DMD to form a sequence of patterns, said sequence formed by providing a first plurality of said mirrors in an ON state for a first amount of time and by providing a second plurality of mirrors in an ON state for a second amount of time different than said first amount of time, wherein neither said first amount of time nor said second amount of time is a zero amount; and

e) firing said laser at said DMD such that said laser beam is directed by said DMD to contact said cornea in said sequence of patterns.

22. A method according to claim 21, wherein:

said sequence formed by further providing a third plurality of said mirrors in an ON state for a zero amount of time.

23. A method according to claim 21, wherein:

said laser is a continuous wave laser.

24. A laser surgery system for reshaping the corneal of the eye, said system comprising:

a) a wavefront sensor analysis system which generates wavefront sensor analysis data;

b) a computer system coupled to said wavefront sensor analysis system and adapted to define a correction for the eye based on said wavefront sensor analysis data;

c) a laser coupled to said computer system and adapted to reshape a portion of a cornea of the eye;

d) a digital micromirror device (DMD) having a plurality of mirrors adapted to modulate a laser beam produced by said laser such that the cornea of the eye is reshaped according to the correction; and

e) a beamsplitter positioned in a first optical path between said DMD and the eye, and in a second optical path between said wavefront sensor analysis system and the eye,

wherein said laser is adapted to produce a laser light beam at a first wavelength, said wavefront sensor analysis system is adapted to generate a light beam at a second wavelength different than said first wavelength, and said beamsplitter is adapted to transmit said laser light beam at said first wavelength from said laser to the cornea of the eye and to reflect said light beam at said second wavelength of light from said wavefront sensor analysis system to the eye and further reflect light at said second wavelength from the eye back to said wavefront sensor analysis system.

25. A laser surgery system for reshaping the corneal of the eye, said system comprising:

a) a wavefront sensor analysis system which generates wavefront sensor analysis data incorporating an alignment marker which correlates the data with a physiological location on the eye;

b) a computer system coupled to said wavefront sensor analysis system and adapted to define a correction for the eye based on said wavefront sensor analysis data and to define a sequence of ablation patterns based upon said correction;

c) a laser coupled to said computer system and adapted to reshape a portion of a cornea of the eye; and

d) a digital micromirror device (DMD) having a plurality of mirrors adapted to modulate a laser beam produced by said laser in a sequence of patterns,

wherein said computer is adapted to adjust said mirrors in said patterns based on said alignment marker.

26. A method for correcting the shape of a cornea of an eye to improve vision, said method comprising:

a) providing a laser surgery system adapted to perform corrective surgery on the cornea of the eye, said laser surgery system including a laser and a digital micromirror device (DMD) including a plurality of mirrors adapted to modulate a laser beam produced by said laser, said DMD positionable between said laser and the eye;

b) providing a wavefront sensor;

c) measuring the eye with the wavefront sensor such that wavefront analysis data is provided;

d) utilizing said wavefront analysis data to define a correction profile;

e) creating a sequence of patterns from said correction profile for said laser beam, each of said patterns representing a particular layer of the cornea to be corrected;

f) directing said mirrors of said DMD to form a one or more of said patterns of said sequence of patterns;

g) for each of said patterns into which said mirrors are directed, firing said laser at said DMD such that said laser beam is directed by said DMD to contact said cornea in said pattern; and

h) repeating steps c) through g) such that feedback is provided during the course of correcting the shape of a cornea.

27. A method according to claim 26, wherein:

incorporating an alignment marker in said wavefront sensor data which correlates the wavefront sensor data with a physiological location on the eye.