Method for scanning a pulsed laser beam

Patent metadata

Field	Value
Publication number	US-9226853-B2
Application number	US-201514660345-A
Country	US
Kind code	B2
Filing date	Mar 17, 2015
Priority date	Jan 2, 2008
Publication date	Jan 5, 2016
Grant date	Jan 5, 2016

Abstract

Methods of photoaltering a region of a material using a pulsed laser beam. The method includes scanning the pulsed laser beam in a first portion of the region with a first pattern, scanning the pulsed laser beam in a second portion of the region with a second pattern, and separating a flap of the material at the region. The system includes a laser, a controller selecting at least first and second patterns, and a scanner operable in response to the controller. The first pattern has a first maximum acceleration associated with the second portion, and the second pattern has a second maximum acceleration associated with the second portion. The second maximum acceleration is less than the first maximum acceleration. The scanner scans the pulsed laser beam from the laser in the first portion with the first pattern and in the second portion with the second pattern.

First claim

What is claimed is:

1. A method of photoaltering a sub-surface area of a patient's cornea using a pulsed laser beam, the sub-surface area having a first region and a second region which is a central region surrounded by the first region, the method comprising the steps of:
transmitting the pulsed laser beam with a scanner to the first region of the sub-surface area of the cornea in accordance with only a first laser scan pattern based on a continuous scan of the pulsed laser beam, the first laser scan pattern continuing until an acceleration associated with scanning the first laser scan pattern reaches a pre-determined maximum limit; and
after the first laser scan pattern reaches the pre-determined maximum limit of the acceleration associated therewith, transmitting the pulsed laser beam with a scanner to the second region of the sub-surface area of the cornea in accordance with only a second laser scan pattern based on a continuous scan of the pulsed laser beam that is different than the first laser scan pattern, the second laser scan pattern having an associated acceleration that is less than the pre-determined maximum limit, and wherein the first region and the second region combine to span the entire sub-surface area of the cornea.

2. The method of claim 1 , wherein the method creates a corneal flap and includes separating the corneal flap from underlying corneal tissue while leaving one edge connected as a hinge.

3. The method of claim 2 , further including transmitting the pulsed laser beam to create a side cut around a desired perimeter of the flap while leaving an uncut segment to serve as the hinge for the flap, and wherein transmission of the pulsed laser beam in the first and second laser scan patterns forms a resection bed the perimeter of which is approximately defined by and slightly greater than the side cut.

4. The method of claim 1 , wherein the first laser scan pattern comprises a spiral laser scan pattern beginning from an outer periphery of the sub-surface area of the cornea and successively tracing smaller rotations toward a center of the area of the cornea.

5. The method of claim 4 , wherein the step of transmitting the pulsed laser beam in a spiral laser scan pattern is done at a speed that permits sufficient time for ablation gas to either cool down or to migrate away before the next smaller rotation of the spiral laser scan pattern so as to reduce and/or eliminate formation of an opaque bubble layer (OBL) in a corneal flap bed.

6. The method of claim 1 , wherein the step of transmitting the pulsed laser beam in the second region comprises transmitting the pulsed laser beam in accordance with a second laser scan pattern selected from the group consisting of:
an uninterrupted compound laser scan pattern;
a traveling circular laser scan pattern;
a sinusoidal laser scan pattern;
hypotrochoid laser scan pattern; and
a progressive oval laser scan pattern.

7. The method of claim 1 , wherein the step of transmitting the pulsed laser beam in the second region comprises transmitting the pulsed laser beam in accordance with a raster scan pattern.

8. The method of claim 7 , wherein the first laser scan pattern is a spiral scan pattern that has an outer diameter of about 8.5 mm and reaches the pre-determined maximum limit of the acceleration associated therewith at a diameter of about 7 mm, and wherein the raster scan pattern has a diameter larger than 7 mm such that there is an overlap between the two scan patterns.

9. The method of claim 1 , wherein the first laser scan pattern and second laser scan pattern are defined over a dome-shaped area of the sub-surface area of the cornea.

10. A method of photoaltering a sub-surface area of a patient's cornea using a pulsed laser beam, the sub-surface area having an outer periphery, a first region defined within and circumscribed by the outer periphery, and a second region which is a central region surrounded by the first region, the method comprising the steps of:
transmitting the pulsed laser beam with a scanner to the first region of the sub-surface area of the cornea in accordance with only a spiral laser scan pattern based on a continuous scan of the pulsed laser beam, the spiral laser scan pattern commencing at the outer periphery of the sub-surface region and progressively rotating inward toward a central region thereof, the spiral laser scan pattern continuing until a predetermined diameter is reached; and
after the spiral laser scan pattern reaches the pre-determined diameter, transmitting the pulsed laser beam with a scanner to the second region of the sub-surface area of the cornea in accordance with only a second laser scan pattern based on a continuous scan of the pulsed laser beam and that is different than the first laser scan pattern, the second laser scan pattern having an associated acceleration that is less than the pre-determined maximum limit, and wherein the first region and the second region combine to span the entire sub-surface area of the cornea.

11. The method of claim 10 , wherein the method creates a corneal flap and includes separating the corneal flap from underlying corneal tissue while leaving one edge connected as a hinge.

12. The method of claim 11 , further including transmitting the pulsed laser beam to create a side cut around a desired perimeter of the flap while leaving an uncut segment to serve as the hinge for the flap, and wherein transmission of the pulsed laser beam in the first and second laser scan patterns forms a resection bed the perimeter of which is approximately defined by and slightly greater than the side cut.

13. The method of claim 10 , wherein at least some of the second scan pattern overlaps at least some of the first scan pattern to form an overlapped region, and wherein the step of transmitting the pulsed laser beam in the second region comprises blanking the pulsed laser beam while the pulsed laser beam is in the overlapped region.

14. The method of claim 10 , wherein the step of transmitting the pulsed laser beam in a spiral laser scan pattern is done at a speed that permits sufficient time for ablation gas to either cool down or to migrate away before the next smaller rotation of the spiral laser scan pattern so as to reduce and/or eliminate formation of an opaque bubble layer (OBL) in a corneal flap bed.

15. The method of claim 10 , wherein the step of transmitting the pulsed laser beam in the second region comprises transmitting the pulsed laser beam in accordance with a second laser scan pattern selected from the group consisting of:
an uninterrupted compound laser scan pattern;
a traveling circular laser scan pattern;
a sinusoidal laser scan pattern;
hypotrochoid laser scan pattern; and
a progressive oval laser scan pattern.

16. The method of claim 10 , wherein the step of transmitting the pulsed laser beam in the second region comprises transmitting the pulsed laser beam in accordance with a raster scan pattern.

17. The method of claim 16 , wherein the first laser scan pattern is a spiral scan pattern that has an outer diameter of about 8.5 mm and reaches the pre-determined maximum limit of the acceleration associated therewith at a diameter of about 7 mm, and wherein the raster scan pattern has a diameter larger than 7 mm such that there is an overlap between the two scan patterns.

18. The method of claim 10 , wherein the first laser scan pattern and second laser scan pattern are defined over a dome-shaped area of the sub-surface area of the cornea.

19. The method of claim 10 , wherein the pre-determined diame

Assignees

• Amo Dev Llc
• Amo Dev Llc

Inventors

• Bor Zsolt
• Zadoyan Ruben
• Bouvier Marcel
• Holland Guy V

Classifications

• B23K26/08

  Devices involving relative movement between laser beam and workpiece · CPC title

• A61F2009/00882

  based on topography · CPC title

• A61F2009/00897

  Scanning mechanisms or algorithms · CPC title

• A61F2009/0088

  based on wavefront · CPC title

• B23K26/0084

  Operations & Transport · mapped topic