Iris pattern recognition and alignment

• US 7,331,667 B2
• Filed: 05/10/2001
• Issued: 02/19/2008
• Est. Priority Date: 04/27/2001
• Status: Expired due to Term

• Current Assignee: Bausch & Lomb Incorporated (Bausch Health Cos., Inc.)
• Original Assignee: Bausch & Lomb Incorporated (Bausch Health Cos., Inc.)
• Inventors: Grotehusmann, Ulf, Youssefi, Gerhard
• Primary Examiner(s): Stultz; Jessica T
• Application Number:
  US10/474,958
• Publication Number:
  US 20040169817A1
• Time in Patent Office: 2,476 Days
• Field of Search: 351/205
• US Class Current: 351/205
• CPC Class Codes: A61B 3/152 for aligning
• CPC Class Codes: A61B 5/1171 based on the shapes or appearances of their bodies or parts thereof
• CPC Class Codes: G06V 40/19 Sensors therefor

Abstract

Apparatus and methods are described for aligning diagnostic and therapeutic iris images, via iris pattern recognition, for effecting more accurate laser treatment of the eye. A method for aligning a dilated pupil diagnostic iris image associated with a diagnostic measurement for calculating a laser treatment, with a constricted pupil diagnostic iris image, by identifying an iris landmark that is not identifiable solely between the two images, includes a sequential plurality of diagnostic iris images of varying pupil size such that the iris landmark can be tracked between the two images. The aligned, constricted pupil diagnostic image can then be aligned with a constricted pupil treatment image and the ablation pattern rotated accordingly. Limbal edge detection is used in the diagnostic images to provide pupil center translation information for translational alignment of the laser treatment. An improved aberrometer is disclosed having a variable visible illumination fixation target for controlling pupil size for the diagnostic images. A diagnostic and therapeutic laser eye treatment system is described incorporating the apparatus and method embodiments of the invention.

Claims

1. A method for aligning a diagnostic iris image of a patient'"'"'s eye having a dilated pupil with a treatment iris image of the eye having a constricted pupil, via an iris pattern recognition technique, wherein an iris recognition landmark in the dilated pupil diagnostic image is not directly identifiable with the corresponding iris recognition landmark in the constricted pupil treatment iris image, to effect an accurate laser treatment of the patient'"'"'s eye that is derived from a diagnostic measurement associated with the dilated pupil, characterized by:

visibly illuminating the patient'"'"'s eye with a plurality of selected levels of visible illumination to effect a corresponding plurality of different pupil sizes ranging from a constricted pupil diameter to a dilated pupil diameter;

respectively obtaining a sequential plurality of diagnostic iris images each of which has an indicia of the iris recognition landmark;

correlating the indicia of the iris recognition landmark in each sequential diagnostic iris image such that the iris recognition landmark in the constricted pupil diagnostic iris image is identifiable with the iris recognition landmark in the dilated pupil diagnostic iris image;

making a diagnostic measurement of the patient'"'"'s eye and the associated diagnostic image when the pupil is dilated;

obtaining a treatment iris image of the patient'"'"'s eye having a constricted pupil;

aligning the constricted diagnostic iris image with the constricted pupil treatment iris image.

2. The method of claim 1, further characterized by adjusting the laser treatment on the eye based upon the iris alignment.

3. The method of claim 1, wherein making the diagnostic measurement includes obtaining an indication of a wavefront aberration and an axis of astigmatism.

4. The method of claim 3, wherein making the diagnostic measurement comprises using one of an elevation based topographer, optical raytracing, and an aberrometer.

5. The method of claim 1, wherein the aligning comprises correlating the dilated pupil diagnostic iris image with the constricted pupil diagnostic iris image and comparing an aligned constricted pupil diagnostic iris image with the constricted pupil treatment image.

6. The method of claim 1, wherein the aligning comprises comparing the plurality of diagnostic iris images with the treatment iris image to align the constricted pupil diagnostic iris image with the constricted pupil treatment iris image.

7. The method of claim 1, wherein the laser treatment is directed to one of a myopia correcting ablation, a hyperopia correcting ablation, an astigmatism correcting ablation, a custom corneal ablation, a retinal ablation, and another laser eye surgery procedure.

8. The method of claim 1, further characterized by determining an illumination independent reference landmark on the eye;

calculating a center position of the pupil with respect to the reference landmark associated with the dilated pupil diagnostic iris image;

calculating a center position of the pupil with respect to the reference landmark associated with the constricted pupil diagnostic iris image;

determining a vector displacement value for the constricted pupil center and the dilated pupil center;

adjusting the laser treatment to be performed on the constricted pupil eye with respect to the vector displacement of the dilated pupil center.

9. The method of claim 8, wherein the illumination independent reference landmark is a portion of the limbus of the eye.

10. The method of claim 9, wherein the portion of the limbus is a limbal edge.

11. In a diagnostic and therapeutic system for laser eye surgery wherein a diagnostic image of a patient'"'"'s eye that is obtained by a diagnostic image capture is aligned with a treatment image of the patient'"'"'s eye that is obtained by a treatment image capture device that is associated with a treatment laser system, via an iris pattern recognition technique, the improvement characterized by:

an illumination control device for controlling a visible illumination level on one of the patient'"'"'s eye being examined and the patient'"'"'s other eye, not being examined, wherein the visible illumination level acts as a control for the pupil diameter of the examined eye;

a sequential plurality of diagnostic iris images each including a different pupil diameter ranging between a dilated pupil size and a constricted pupil size corresponding to the controlled visible illumination level, wherein at least an indicia of an iris recognition landmark is identifiable in each sequential diagnostic iris image even though the corresponding iris recognition landmark is not identifiable between the constricted diagnostic pupil image and the dilated diagnostic pupil image;

an eye diagnostic measuring device for obtaining a diagnostic measurement of the patient'"'"'s eye associated with the dilated diagnostic pupil image, cooperatively associated with the illumination control device and the diagnostic image capture device;

means for exporting at least one of the diagnostic iris images to the laser treatment system; and

means for aligning the dilated pupil diagnostic iris image with the constricted pupil diagnostic iris image, and further for aligning the aligned constricted pupil diagnostic iris image with the treatment iris image having a constricted pupil of a size generally corresponding to the diagnostic image constricted pupil size.

12. The system of claim 11, wherein the means for aligning includes a treatment stage processor cooperatively engaged with the treatment image capture device.

13. The system of claim 11, wherein the means for exporting includes at least one of a wired connection, a wireless connection, a computer file storage medium.

14. The system of claim 11, wherein the diagnostic measurement obtained by the eye diagnostic measuring device is suitable for obtaining a wavefront information about the patient'"'"'s eye.

15. The system of claim 11, wherein the eye diagnostic measuring device includes the iris image capture device.

16. The system of claim 11, wherein the illumination control device is separate from the diagnostic measuring device.

17. The system of claim 11, wherein the illumination control device comprises a variable illumination fixation target and is an integrated component of the diagnostic measuring device.

18. The system of claim 11, wherein the improvement is further characterized by a means for obtaining a vector displacement measurement between a pupil center of the dilated pupil diagnostic image and the pupil center of the constricted pupil diagnostic image.

19. The system of claim 18, wherein the vector displacement measurement is a measurement from limbus reference position to the center of the pupil.

20. In a diagnostic and therapeutic system for laser eye surgery wherein a diagnostic image of a patient'"'"'s eye that is obtained by a diagnostic image capture device that is also adapted to make a diagnostic measurement of the patient'"'"'s eye, is aligned with a treatment image of the patient'"'"'s eye that is obtained by a treatment image capture device which is associated with a treatment laser system, via an iris pattern recognition technique, the improvement characterized by:

an illumination control device for controlling a visible illumination level on one of the patient'"'"'s eye being examined and the patient'"'"'s other eye, not being examined, wherein the visible illumination level acts as a control for the pupil diameter of die examined eye;

a sequential plurality of diagnostic iris images each including a different pupil diameter ranging between a dilated pupil size and a constricted pupil size corresponding to the controlled visible illumination level, obtained by the diagnostic image capture device, wherein an iris recognition landmark is identifiable in each sequential diagnostic iris image even though the corresponding iris recognition landmark is not identifiable between the constricted diagnostic pupil image and the dilated diagnostic pupil image;

means for exporting at least one of the diagnostic iris images to the laser treatment system;

means for aligning the dilated pupil diagnostic iris image, associated with a diagnostic measurement image, with the constricted pupil diagnostic iris image; and

means for aligning the aligned constricted pupil diagnostic iris image with the treatment iris image having a constricted pupil of a size generally corresponding to the diagnostic image constricted pupil size.

21. The system of claim 20, wherein the means for aligning the dilated pupil diagnostic iris image with the constricted pupil diagnostic iris image includes a diagnostic stage processor cooperatively engaged with the diagnostic image capture device.

22. The system of claim 21, wherein the means for exporting includes at least one of a wired connection, a wireless connection, a computer file storage medium.

23. The system of claim 20, wherein the diagnostic measurement obtained by the eye diagnostic measuring device is suitable for obtaining a wavefront information about the patient'"'"'s eye.

24. The system of claim 20, wherein the eye diagnostic measuring device includes the iris image capture device.

25. The system of claim 20, wherein the illumination control device is separate from the diagnostic measuring device.

26. The system of claim 20, wherein the illumination control device comprises a variable illumination fixation target and is an integrated component of the diagnostic measuring device.

27. The system of claim 20, wherein the improvement is further characterized by a means for obtaining a vector displacement measurement between a pupil center of the dilated pupil diagnostic image and the pupil center of the constricted pupil diagnostic image.

28. The system of claim 21, wherein the vector displacement measurement is a measurement from limbus reference position to the center of the pupil.