Method for intrastromal refractive surgery

• US 7,717,907 B2
• Filed: 12/17/2007
• Issued: 05/18/2010
• Est. Priority Date: 12/17/2007
• Status: Active Grant

• Current Assignee: Technolas Perfect Vision GMBH (Bausch Health Cos., Inc.)
• Original Assignee: Technolas Perfect Vision GMBH (Bausch Health Cos., Inc.)
• Inventors: Bille, Josef F., Ruiz, Luis Antonio
• Primary Examiner(s): Johnson, III; Henry M
• Assistant Examiner(s): LIPITZ, JEFFREY BRIAN
• Application Number:
  US11/958,202
• Publication Number:
  US 20090157061A1
• Time in Patent Office: 883 Days
• Field of Search: 606/5
• US Class Current: 606/5
• CPC Class Codes: A61F 2009/00872 Cornea
• CPC Class Codes: A61F 2009/00895 Presbyopia
• CPC Class Codes: A61F 2009/00897 Scanning mechanisms or algorithms
• CPC Class Codes: A61F 9/008 using laser
• CPC Class Codes: A61F 9/00827 Refractive correction, e.g. lenticle
• CPC Class Codes: A61F 9/00838 Correction of presbyopia

Abstract

A method for performing intrastromal ophthalmic laser surgery requires Laser Induced Optical Breakdown (LIOB) of stromal tissue without compromising Bowman'"'"'s capsule (membrane). In detail, the method creates cuts in the stroma over all, or portions of, a plurality of concentric cylindrical surfaces (circular or oval). Importantly, these cuts are all centered on the visual axis of the patient'"'"'s eye. In accordance with the present invention, cuts can be made either alone or in conjunction with the removal of predetermined volumes of stromal tissue. The actual location of cuts in the surgery will depend on whether the treatment is for presbyopia, myopia, hyperopia or astigmatism.

Claims

1. A method for performing intrastromal ophthalmic laser surgery, wherein the cornea defines a visual axis and has a thickness “

T”

, and wherein the method comprises the steps of;

generating a pulsed laser beam, wherein the duration of each pulse in the beam is less than approximately one picosecond;

directing and focusing the beam onto a series of focal spots in the stroma for Laser Induced Optical Breakdown (LIOB) of stromal tissue at each focal spot to weaken stromal tissue by redistributing biomechanical forces in the stroma; and

moving the focal spot in the stroma to create a plurality of unconnected cuts, wherein each cut is made on portions of a respective cylindrical surface to remove an insignificant amount of tissue to substantially maintain the integrity of the cornea, wherein the respective cylindrical surfaces are concentric and are centered on the visual axis of the cornea, and further wherein each cylindrical surface has an anterior end and a posterior end, with the posterior end of the cut being located in the stroma less than approximately 0.9 T from an anterior surface of the eye, and the anterior end of the cylindrical cut is located in the stroma more than at least eight microns in a posterior direction from Bowman'"'"'s capsule in the cornea, with the weakened stromal tissue being responsive to an intraocular pressure for surgically reshaping the cornea.

2. A method as recited in claim 1 wherein each cut is approximately two hundred microns from an adjacent cut.

3. A method as recited in claim 1 wherein the plurality of cuts are at least 1.0 millimeters from the visual axis.

4. A method as recited in claim 1 wherein the portions of the cylindrical surfaces subjected to LIOB define diametrically opposed arc segments wherein each arc segment extends through an arc in a range between five degrees and one hundred and sixty degrees.

5. A method as recited in claim 1 wherein the portions of the cylindrical surfaces subjected to LIOB define a complete cylindrical shaped wall.

6. A method as recited in claim 1 wherein each pulse of the laser beam has an energy of approximately 1.2 microJoules.

7. A method as recited in claim 1 further comprising the steps of:

performing LIOB in portions of an annular layer, wherein the layer has an inner diameter “

d_i” and

an outer diameter “

d_o”

, and has a thickness of about one micron;

creating a plurality of layers adjacent to each other; and

locating the plurality of layers in the stroma between less than approximately 0.9 T from the anterior surface of the eye and at least eight microns in a posterior direction from Bowman'"'"'s capsule.

8. A method as recited in claim 7 wherein the plurality of cuts is distanced from the visual axis by a radial distance “

r_c”

, wherein “

d_i”

of the plurality of layers is zero, and “

d_o”

of the plurality of layers is less than 2r_c (d_0<

2r_c).

9. A method as recited in claim 7 wherein the plurality of cuts is distanced from the visual axis in a range between “

r_ci” and

“

r_co”

, wherein r_co>

r_ci, and further wherein “

d_i”

of the plurality of layers is greater than 2r_co (d_o>

d_i>

2r_co).

10. A method as recited in claim 7 wherein energy for each pulse in the moving step is approximately 1.2 microJoules, and the energy for each pulse in the performing step is approximately 0.8 microJoules.

11. A method for performing intrastromal ophthalmic laser surgery, wherein the cornea defines a visual axis and has a thickness “

T”

, and wherein the method comprises the steps of;

identifying an operational volume in the stroma, wherein the operational volume is centered on the visual axis and extends radially therefrom through a distance “

r_v”

, and further wherein the operational volume has an anterior surface located at least eight microns in a posterior direction from Bowman'"'"'s capsule (membrane) of the cornea and a posterior surface located at less than approximately 0.9 T from the anterior surface of the cornea;

focusing a pulsed laser beam to a focal point in the operational volume for LIOB of stromal tissue, wherein each pulse of the laser beam has a duration less than one picosecond to weaken stromal tissue by redistributing biomechanical forces in the stroma; and

moving the focal spot within the operational volume to create a plurality of unconnected cuts, wherein each cut is made on portions of a respective cylindrical surface to remove an insignificant amount of tissue to substantially maintain the integrity of the cornea, wherein the respective cylindrical surfaces are concentric and are centered on the visual axis of the cornea, and further wherein each cylindrical surface has an anterior end and a posterior end, with the weakened stromal tissue being responsive to an intraocular pressure for surgically reshaping the cornea.

12. A method as recited in claim 11 wherein each cut is approximately two hundred microns from an adjacent cut and wherein the plurality of cuts are at least 1.4 millimeters from the visual axis.

13. A method as recited in claim 11 wherein the portions of the cylindrical surfaces subjected to LIOB define diametrically opposed arc segments wherein each arc segment extends through an arc in a range between five degrees and one hundred and sixty degrees.

14. A method as recited in claim 11 further comprising the steps of:

performing LIOB in portions of an annular layer, wherein the layer has an inner diameter “

d_i” and

an outer diameter “

d_o”

, and has a thickness of about two microns;

creating a plurality of layers adjacent to each other; and

locating the plurality of layers in the stroma between less than approximately 0.9 T from the anterior surface of the eye and at least eight microns in a posterior direction from Bowman'"'"'s capsule.

15. A method as recited in claim 14 wherein the plurality of cuts is distanced from the visual axis by a radial distance “

r_c”

wherein “

d_i”

of the plurality of layers is zero, and “

d_o”

of the plurality of layers is less than 2r_c (d₀<

2r_c).

16. A method as recited in claim 14 wherein the plurality of cuts is distanced from the visual axis in a range between “

r_ci” and

“

r_co”

, wherein r_co>

r_ci, and further wherein “

d_i”

of the plurality of layers is greater than 2r_co (d_o>

d_i>

2r_co).

17. A method as recited in claim 14 wherein energy for each pulse in the moving step is approximately 1.2 microJoules, and the energy for each pulse in the performing step is approximately 0.8 microJoules.

18. A method for performing intrastromal ophthalmic laser surgery, wherein the cornea defines a visual axis and has a thickness “

T”

, and wherein the method comprises the steps of;

generating a pulsed laser beam, wherein the duration of each pulse in the beam is less than one picosecond;

directing and focusing the beam onto a series of focal spots in the stroma for Laser Induced Optical Breakdown (LIOB) of stromal tissue at each focal spot to weaken stromal tissue by redistributing biomechanical forces in the stroma; and

moving the focal spot in the stroma to create a first plurality of cuts and a second plurality of unconnected cuts, wherein each cut is made on portions of a respective cylindrical surface to remove an insignificant amount of tissue to substantially maintain the integrity of the cornea, wherein the respective cylindrical surfaces in the first plurality are concentric on a first axis, wherein the first axis is parallel to the visual axis, and wherein the cylindrical surfaces in the second plurality are centered on a second axis, wherein the second axis is parallel to the visual axis and opposite the first axis therefrom, and further wherein each cylindrical surface has an anterior end and a posterior end, with the posterior end of the cut being located in the stroma less than approximately 0.9 T from an anterior surface of the eye, and the anterior end of the cylindrical cut is located in the stroma more than at least eight microns in a posterior direction from Bowman'"'"'s capsule in the cornea, with the weakened stromal tissue being responsive to an intraocular pressure for surgically reshaping the cornea.

19. A method as recited in claim 18 further comprising the steps of:

performing LIOB in portions of an annular layer, wherein the layer has an inner diameter “

d_i” and

an outer diameter “

d_o”

, and has a thickness of about two microns;

creating a plurality of layers adjacent to each other; and

locating the plurality of layers in the stroma between less than approximately 0.9 T from the anterior surface of the eye and at least eight microns in a posterior direction from Bowman'"'"'s capsule.

20. A method as recited in claim 19 wherein energy for each pulse in the moving step is approximately 1.2 microJoules, and the energy for each pulse in the performing step is approximately 0.8 microJoules.

21. A method for performing intrastromal ophthalmic laser surgery to weaken stromal tissue by redistributing biomechanical forces in the stroma, wherein the cornea defines a visual axis and has a thickness “

T”

, and wherein the method comprises the steps of;

generating a pulsed laser beam, wherein the duration of each pulse in the beam is less than approximately one picosecond;

directing and focusing the beam onto a series of focal spots in the stroma for Laser Induced Optical Breakdown (LIOB) of stromal tissue at each focal spot; and

moving the focal spot in the stroma to create a plurality of unconnected radial cuts to remove an insignificant amount of tissue to substantially maintain the integrity of the cornea, wherein each cut is made coplanar with the visual axis and is defined by an azimuthal angle θ

, wherein each radial cut has an anterior end and a posterior end extending from an inner radius “

r_i”

to an outer radius “

r_o”

, with both “

r_i” and

“

r_o”

being measured from the visual axis, with the posterior end of the cut being located in the stroma within less than approximately 0.9 T from an anterior surface of the eye, and the anterior end of the radial cut is located in the stroma more than at least eight microns in a posterior direction from Bowman'"'"'s capsule, and further wherein the radial cut has a thickness of approximately two microns, with the weakened stromal tissue being responsive to an intraocular pressure for surgically reshaping the cornea.