SYSTEMS AND METHODS FOR IMPROVED OPHTHALMIC IMAGING

• US 20120274897A1
• Filed: 04/23/2012
• Published: 11/01/2012
• Est. Priority Date: 04/27/2011
• Status: Active Grant

• Current Assignee: Carl Zeiss Meditec Incorporated (Carl-Zeiss-Stiftung)
• Original Assignee: Carl Zeiss Meditec Incorporated (Carl-Zeiss-Stiftung)
• Inventors: Meyer, Scott A., NARASIMHA-IYER, Harihar
• Granted Patent: US 9,055,892 B2
• Time in Patent Office: Days
• US Class Current: 351/206
• CPC Class Codes: A61B 3/102 for optical coherence tomography [OCT]
• CPC Class Codes: A61B 3/113 for determining or recording eye movement
• CPC Class Codes: A61B 3/117 for examining the anterior chamber or the anterior chamber angle, e.g. gonioscopes
• CPC Class Codes: A61B 3/12 for looking at the eye fundus, e.g. ophthalmoscopes A61B3/13 takes precedence
• CPC Class Codes: A61B 3/152 for aligning

Abstract

Systems and methods for improving ophthalmic imaging by correlating the location of a measurement on the pupil of the eye with a quality of the measurement and further controlling subsequent measurements based on the quality are presented. Aspects of the invention include obtaining optical coherence tomography (OCT) measurements through cataracts or other media opacities, obtaining B-scans with minimized tilt, and automated OCT data acquisition of select structures in the eye. Embodiments of the invention directed towards imaging tissues with angle dependent layer contrast and mapping the size and location of cataracts in the eye are also described.

Claims

1. A method to obtain ophthalmic measurement data, the method comprising:

collecting a plurality of measurements at different entry locations on the pupil of a subject, wherein there is a relationship between the coordinates of the measurement system and the pupil entry location;

determining a representative value for each measurement that characterizes a quality of the measurement;

identifying the best representative value and its corresponding pupil entry location; and

controlling the measurement system to acquire subsequent measurements at the pupil entry location corresponding to the best representative value determined.

2. A method as recited in claim 1, wherein the plurality of measurements are OCT A-scans.

3. A method as recited in claim 2, wherein the quality of the measurement is the signal to noise ratio.

4. A method as recited in claim 3, wherein the best representative value is the value with the highest signal to noise ratio.

5. A method as recited in claim 1, wherein the plurality of measurements are OCT B-scans

6. A method as recited in claim 5, wherein the quality of the measurement is the tilt of the B-scan.

7. A method as recited in claim 6, wherein the best representative value is the value with the least amount of tilt.

8. A method as recited in claim 1, further comprising correcting for movement of the retina.

9. A method as recited in claim 1, wherein the quality of the measurement is the intensity of the signal.

10. A method as recited in claim 1, wherein the plurality of measurements are taken in the posterior part of the eye.

11. A method as recited in claim 1, wherein the plurality of measurements are taken in the anterior part of the eye.

12. A method as recited in claim 1, wherein the subsequent measurements are taken at a follow-up visit.

13. A method as recited in claim 1, where in the pupil entry location is chosen to optimize the visualization of a particular structure in the eye.

14. A method as recited in claim 1, where in the pupil entry location is chosen to avoid media opacities.

15. A method as recited in claim 1, wherein the pupil entry location is determined and controlled using an image of the eye containing the pupil.

16. A method as recited in claim 1, wherein the best representative value is identified from representative values characterizing more than one quality of the measurement.

17. A method as recited in claim 1, wherein the best representative value is identified by a user based on a display of the representative values.

18. A method as recited in claim 1, wherein the pupil entry location is chosen to optimize the visualization of abnormalities at the anterior surface of the retina.

19. A method as recited in claim 1, further comprising adjusting the pupil entry location to account for pupil constriction and dilation

20. A method of collecting image data of an eye of a patient using an ophthalmic imaging system, said imaging system including a scanner for directing a beam of radiation through the pupil, said method comprising:

selecting a preferred location on the pupil for the entry of the beam of radiation;

monitoring the motion of the eye; and

adjusting the positioning of the beam of radiation in response to the monitored motion to maintain the preferred pupil entry location while capturing image data of structures within the eye.

21. A method as recited in claim 20, wherein the ophthalmic imaging system is an optical coherence tomography (OCT) system.

22. A method as recited in claim 21, wherein the step of monitoring the motion of the eye includes imaging the pupil with an imaging system and determining the location of the pupil from within the image.

23. A method as recited in claim 22, wherein the selected pupil entry location is the center of the pupil.

24. A method as recited in claim 22, wherein the pupil entry location is selected by the user.

25. A method as recited in claim 22, wherein the pupil entry location is selected and maintained based on the boundaries of the pupil identified in the image.

26. A method as recited in claim 22, wherein the pupil entry location is adjusted to account for pupil constriction and dilation.

27. A method as recited in claim 22, wherein the selected pupil entry location is the same location as measurements acquired at a previous examination of the patient.

28. An automated method for evaluating tissue in Optical Coherence Tomography (OCT) images of the eye, the method comprising:

acquiring intensity data from multiple OCT B-scans of the eye, said B-scans being taken at two or more different angles of incidence relative to tissue in eye;

processing the intensity data to identify the differences in the data due to the difference in angles of incidence; and

storing or displaying the identified differences.

29. A method as recited in claim 28, wherein said step of processing the intensity data includes registering images derived from the intensity data at different angles of incidence and generating an image which displays the differences in intensity data.

30. A method as recited in claim 28, wherein said step of processing the intensity data includes determining tissue characteristics based on the identified differences.

31. A method as recited in claim 30, wherein said tissue characteristic is a layer thickness.

32. A method as recited in claim 28, wherein said step of processing the intensity data includes evaluating the intensity data to determine a scattering profile as a function of depth.

36. A method as recited in claim 32, wherein the collection of representative values is compared to representative values determined at a different examination of the patient.

33. A method to analyze opacities in the eye of the patient said method comprising:

collecting a plurality of measurements at different entry locations on the pupil of a subject, wherein there is a relationship between the coordinates of the measurement system and the pupil entry location;

determining a representative value for each measurement that reflects a quality of the opacity; and

displaying or storing the collection of representative values.

34. A method as recited in claim 33, wherein the opacity is a cataract.

35. A method as recited in claim 34, wherein the quality of the opacity is density.

37. A method of collecting 3D image data of an eye of a patient using an optical coherence tomography (OCT) system, said OCT system including a scanner for directing a beam of radiation through the pupil and a processor for analyzing OCT data, said method comprising the steps of:

obtaining a series of measurements with the OCT system wherein the beam of radiation is directed to enter the pupil at different locations;

comparing the quality of the series of measurements in the processor to determine the optimum pupil entry location;

capturing 3D image data of structures within the eye with the radiation beam being positioned at the determined optimum pupil entry location; and

storing or displaying the 3D image data.

38. A method as recited in claim 37, wherein the optimum pupil location is based upon a determination of the highest signal to noise ratio.

39. A method as recited in claim 37, wherein the optimum pupil location is based upon obtaining the least amount of tilt in the structure of the eye being imaged.

40. A method as recited in claim 37, wherein the optimum pupil location is based upon avoiding opacities in the eye.

41. A method as recited in claim 37, wherein the pupil entry location controlled using an image of the eye containing the pupil.

42. An ophthalmic diagnostic system for obtaining measurement data at a precise location on the pupil of an eye, said system comprising:

a measurement system comprising a light source to generate a beam of radiation, said measurement system including optics for adjusting the entry position of the beam on the pupil of the eye and for scanning the beam over a set of transverse locations within the eye, said measurement system further including a detector for measuring radiation returning from the eye, the detector generating output signals in response thereto;

an imaging system for capturing images of the pupil; and

a processor for comparing the images from the image system to determine motion of the eye and for adjusting the beam of radiation in response to the monitored motion to maintain the preferred pupil entry position while collecting measurement data.

43. A system as recited in claim 42, wherein the measurement system is an optical coherence tomography (OCT) system.

44. A system as recited in claim 43, wherein the pupil entry location is the center of the pupil.

45. A system as recited in claim 43, wherein the pupil entry position is selected by the user.

46. A system as recited in claim 43, said processor further selecting and maintaining the pupil entry location based on the boundaries of the pupil identified in the image.

47. A system as recited in claim 43, said processor further determining an optimal pupil entry position based on a quality of the measurement data.

48. A system as recited in claim 43, said processor further determining the pupil entry position based on measurement data collected at a previous examination of the eye.