Fast Response Eye Tracking

• US 20080204658A1
• Filed: 05/15/2006
• Published: 08/28/2008
• Est. Priority Date: 05/13/2005
• Status: Active Grant

• Current Assignee: Customvis, PLC
• Original Assignee: Customvis, PLC
• Inventors: Van Saarloos, Paul Philip
• Granted Patent: US 7,922,330 B2
• Time in Patent Office: Days
• US Class Current: 351/210
• CPC Class Codes: A61B 3/113 for determining or recording eye movement
• CPC Class Codes: A61B 3/1216 for diagnostics of the iris
• CPC Class Codes: A61F 2009/00846 Eyetracking
• CPC Class Codes: A61F 2009/00865 Sclera
• CPC Class Codes: A61F 2009/00897 Scanning mechanisms or algorithms
• CPC Class Codes: A61F 9/008 using laser
• CPC Class Codes: A61F 9/00804 Refractive treatments
• CPC Class Codes: A61F 9/00821 for coagulation

Abstract

An apparatus (10) for monitoring the position of an eye during a laser ablation treatment of the eye is provided. The apparatus includes optic means (110) for directing an incident light beam (102) along an optical path (104) onto the external surface of the eye (35) so as to illuminate a region of said surface that includes a segment of the limbus of the eye, and for directing back along said optical path (104), a return beam (122) comprising light of said incident beam scattered by said surface region; beam separation means (125) for separating the return beam (122) from the incident beam (102). The apparatus also includes at least one detector (120), having one or more detector segments (120a, 120b), for detecting said return beam (122), said detector segment(s) (120a, 120b) recording first and second values for light scattered respectively by the sclera and iris in said illuminated region. Movement of said limbal segment, and therefore of the eye (35), produces a change in at least one of said first and second values allowing such movement of the eye (35) to be monitored. A method corresponding to the apparatus is also disclosed.

Claims

1. A method of monitoring the position of an eye during a laser ablation treatment of the eye, the method including:

directing an incident light beam along an optical path onto the external surface of the eye so as to illuminate a region of said surface that includes a segment of the limbus of the eye;

detecting, with at least one detector having one or more detector segments, a return beam comprising light of said incident beam scattered by said surface region, which return beam returns back along said optical path and is separated from the incident beam at beam separation means, said detector segment(s) recording first and second values for light scattered respectively by the sclera and iris in said illuminated region;

whereby movement of said limbal segment, and therefore of the eye, produces a change in at least one of said values.

2. The method of claim 1, wherein said at least one detector has plural detector segments which record said first and second values for light scattered respectively by the sclera and iris, and the detector segments are monitored for change in either or both values.

3. The method of claim 1, wherein said at least one detector has a single detector segment which records both of said first and second values for light scattered respectively by the sclera and iris and the detector segment is monitored for a change in the sum of the values.

4. The method of claim 1, wherein said limbal segment extends substantially radially across the limbus.

5. The method of claim 1, wherein the incident and return beams are scanned over said region and/or limbus segment.

6. A method of treating an eye by laser ablation, the method including determining and/or tracking the position of the eye by monitoring the position of the eye in accordance with the method of claim 1, and adjusting or modifying the ablation responsive to the tracked eye position.

28. The method of claim 2, wherein said limbal segment extends substantially radially across the limbus.

29. The method of claim 28, wherein the incident and return beams are scanned over said region and/or limbus segment.

30. A method of treating an eye by laser ablation, the method including determining and/or tracking the position of the eye by monitoring the position of the eye in accordance with the method of claim 29, and adjusting or modifying the ablation responsive to the tracked eye position.

7. (canceled)

8. An apparatus for monitoring the position of an eye during a laser ablation treatment of the eye, the apparatus including:

optic means for directing an incident light beam along an optical path onto the external surface of the eye so as to illuminate a region of said surface that includes a segment of the limbus of the eye, and for directing back along said optical path, a return beam comprising light of said incident beam scattered by said surface region;

beam separation means for separating the return beam from the incident beam; and

at least one detector, having one or more detector segments, for detecting said return beam, said detector segment(s) recording first and second values for light scattered respectively by the sclera and iris in said illuminated region;

whereby movement of said limbal segment, and therefore of the eye, produces a change in at least one of said values.

9. The apparatus of claim 8, wherein said at least one detector has plural detector segments which record the first and second values for light scattered respectively by the sclera and iris, whereby the detector segments may be monitored for change in either or both values.

10. The apparatus of claim 8, wherein said at least one detector has a single detector segment which records both of said first and second values for light scattered respectively by the sclera and iris, whereby the detector segment may be monitored for a change in the sum of the values.

11. The apparatus of claim 8, wherein said limbal segment extends substantially radially across the limbus.

12. The apparatus of claim 8, including means to scan the incident and return beams over said region and/or limbus segment.

13. An ophthalmic laser ablation apparatus including:

means to accommodate a patient in a position for performing a laser ablation procedure on an eye of the patient;

means for directing a controlled laser beam onto said eye for performing said procedure;

apparatus according to claim 8 for monitoring the position of an eye during a laser ablation treatment of the eye; and

controller means for controlling said laser beam to perform said procedure, which means is responsive to said first and second values recorded by said detector segments.

31. The apparatus of claim 9, wherein said limbal segment extends substantially radially across the limbus.

32. The apparatus of claim 31, including means to scan the incident and return beams over said region and/or limbus segment.

14. An apparatus for monitoring the position of an eye during a laser ablation treatment of the eye, the apparatus including:

means to record an instantaneous image of a first region of the eye of the patient that traverses the limbus of the eye;

means to analyse said image to derive a first indication of the location of the limbus in said first region at first intervals;

first optic means for directing an incident beam along an optical path onto the external surface of the eye so as to illuminate a second region of said surface that includes a segment of the limbus of the eye, and for receiving a return beam comprising light of said incident beam scattered by said second region;

at least one detector, for detecting said return beam and for determining a second indication of the location of the limbus in said second region of said surface, at second intervals substantially shorter than the first intervals;

means responsive to said first indication for accurately monitoring the position of the eye at said first or greater intervals, and to said second indication for updating that position within said first or greater intervals.

15. The apparatus of claim 14, wherein the return beam returns back along the optical path and is separated from the incident beam at beam separation means, and wherein the at least one detector has one or more detector segments, said detector segment(s) recording first and second values for light scattered respectively by the sclera and iris in the illuminated region.

16. The apparatus of claim 15, wherein said at least one detector has plural detector segments which record said first and second values for light scattered respectively by the sclera and iris, whereby the detector segments may be monitored for change in either or both values.

17. The apparatus of claim 15, wherein said at least one detector has a single detector segment which records both of said first and second values for light scattered respectively by the sclera and iris, whereby the detector segment may be monitored for a change in the sum of the values.

18. The apparatus of claim 14, wherein said limbal segment extends substantially radially across the limbus.

19. The apparatus of claim 14, including means to scan the incident and return beams over said region and/or limbus segment.

33. The apparatus of claim 16, wherein said limbal segment extends substantially radially across the limbus.

34. The apparatus of claim 33, including means to scan the incident and return beams over said region and/or limbus segment.

20. A method of monitoring the position of an eye during a laser ablation treatment of the eye, the method including:

recording an instantaneous image of a first region of the eye of the patient that traverses the limbus of the eye;

analysing said image to derive a first indication of the location of the limbus, in said first regions at first intervals;

directing an incident beam along an optical path onto the external surface of the eye so as to illuminate a second region of said surface that includes a segment of the limbus of the eye;

detecting a return beam comprising light of said incident beam scattered by said second region of said surface and determining a second indication of the location of the limbus in said second region of said surface, at second intervals substantially shorter than the first intervals; and

responding to said first indication to accurately monitor the position of the eye at said first or greater intervals, and to said second indication to update that position within said first or greater intervals.

21. The method of claim 20, wherein the return beam returns back along the optical path, the return beam is separated from the incident beam at beam separation means, and the return beam is detected by at least one detector having one or more detector segments, said detector segment(s) recording first and second values for light scattered respectively by the sclera and iris in the illuminated region.

22. The method of claim 21, wherein said at least one detector has plural detector segments which record said first and second values for light scattered respectively by the sclera and iris, whereby the detector segments may be monitored for change in either or both values.

23. The method of claim 21, wherein said at least one detector has a single detector segment which records both of said first and second values for light scattered respectively by the sclera and iris, whereby the detector segment may be monitored for a change in the sum of the values.

24. The method of claim 20, wherein said segment of the limbus of the eye extends substantially radially across the limbus.

25. The method of claim 20, wherein the incident and return beams are scanned over said second region and/or limbus segment.

26. A method of treating an eye by laser ablation, the method including determining and/or tracking the position of the eye by monitoring the position of the eye in accordance with the method of claim 20, and adjusting or modifying the ablation responsive to the tracked eye position.

35. The method of claim 22, wherein said segment of the limbus of the eye extends substantially radially across the limbus.

36. The method of claim 35, wherein the incident and return beams are scanned over said second region and/or limbus segment.

37. A method of treating an eye by laser ablation, the method including determining and/or tracking the position of the eye by monitoring the position of the eye in accordance with the method of claim 36, and adjusting or modifying the ablation responsive to the tracked eye position.

27. (canceled)