Background reduction apparatuses and methods of ocular surface interferometry (OSI) employing polarization for imaging, processing, and/or displaying an ocular tear film

• US 9,999,346 B2
• Filed: 05/08/2017
• Issued: 06/19/2018
• Est. Priority Date: 04/01/2009
• Status: Active Grant

• Current Assignee: TearScience Inc. (Johnson & Johnson)
• Original Assignee: TearScience Inc. (Johnson & Johnson)
• Inventors: Korb, Donald R., Weber, William L., Chinnock, Randal B., Gravely, Benjamin T., Grenon, Stephen M.
• Primary Examiner(s): PINKNEY, DAWAYNE
• Application Number:
  US15/589,146
• Publication Number:
  US 20170238797A1
• Time in Patent Office: 407 Days
• Field of Search: 351206, 351200, 351205, 351209-210, 351221-223, 351245-246, 351212, 351208, 351160 R, 351159, 351247
• CPC Class Codes: A61B 3/0025 characterised by electronic signal processing, e.g. eye models
• CPC Class Codes: A61B 3/0041 characterised by display arrangements
• CPC Class Codes: A61B 3/1005 for measuring distances inside the eye, e.g. thickness of the cornea A61B3/11 takes precedence
• CPC Class Codes: A61B 3/101 for examining the tear film
• CPC Class Codes: A61B 3/14 Arrangements specially adapted for eye photography apparatus or arrangements for taking photographs per se G03B
• CPC Class Codes: G06T 2207/30041 Eye; Retina; Ophthalmic
• CPC Class Codes: G06T 7/0012 Biomedical image inspection

Abstract

Background reduction apparatuses and methods of Ocular Surface Interferometry (OSI) employing polarization are disclosed for measuring a tear film layer thickness (TFLT) of the ocular tear film, including lipid layer thickness (LLT) and/or aqueous layer thickness (ALT) and can be used to evaluate and potentially diagnosis dry eye syndrome (DES). In certain disclosed embodiments, a multi-wavelength light source can be controlled to illuminate the ocular tear film. Light emitted from the multi-wavelength light source undergoes optical wave interference interactions in the tear film. An imaging device can be focused on the lipid layer of the tear film to capture optical wave interference interactions of specularly reflected light from the tear film combined with a background signal(s) in at least one image. The at least one image can be processed and analyzed to measure a tear film layer thickness (TFLT), including lipid layer thickness (LLT) and/or aqueous layer thickness (ALT).

Claims

1. A method of imaging an ocular tear film, comprising:

directing multi-wavelength light including unpolarized light having a first intensity in an illumination path to illuminate a region of interest (ROI) of an ocular tear film thereby producing a specularly reflected light in a first polarization plane, the specularly reflected light containing optical wave interference from the ROI of the ocular tear film while avoiding projecting the multi-wavelength light directly into a pupil of an eye;

polarizing the unpolarized light to cause a background signal comprised of unpolarized light returned from the ROI of the ocular tear film to have a second intensity less than the first intensity;

capturing at least one image of the optical wave interference of specularly reflected light and the background signal from the ROI of the ocular tear film; and

receiving the at least one image containing the optical wave interference of specularly reflected light and the background signal while the multi-wavelength light including the unpolarized light is being polarized.

2. The method of claim 1, wherein reducing the background signal by subtraction is not utilized.

3. The method of claim 1, wherein polarizing attenuates the unpolarized light thereby increasing a ratio of the specularly reflected light to the background signal comprised of the unpolarized light returned from the ROI of the ocular tear film.

4. The method of claim 1, wherein the background signal includes unpolarized light from the ocular tear film comprising at least a portion of the background signal.

5. The method of claim 1, wherein polarizing the unpolarized light decreases intensity of the background signal comprised of the unpolarized light returned from the ROI of the ocular tear film as compared to the intensity of the background signal if a polarizer were not disposed in the illumination path.

6. The method of claim 1, wherein capturing the at least one image of the optical wave interference of specularly reflected light is accomplished by passing the optical wave interference of specularly reflected light through a polarizer disposed in an imaging path of an imaging device.

7. The method of claim 6, wherein the polarizer has a polarization axis aligned parallel or substantially parallel to the specularly reflected light in the first polarization plane from the ROI of the ocular tear film.

8. The method of claim 6, wherein randomly polarized light making up a background signal is reduced by at least 50 percent compared to utilization of the polarizer in the illumination path alone.

9. The method of claim 6, wherein a ratio of specularly reflected light intensity from the ocular tear film to background signal intensity is at least 400 percent.

10. The method of claim 6, wherein illuminating the ROI of the ocular tear film is accomplished by emitting light from a polarized multi-wavelength source through a polarizer disposed in the illumination path between the polarized multi-wavelength light source and the ocular tear film;

and

wherein capturing the at least one image of the optical wave interference of specularly reflected light is accomplished by passing the optical wave interference of specularly reflected light through a second polarizer disposed in the imaging path of the imaging device.

11. The method of claim 10, wherein randomly polarized light making up a background signal is reduced by at least 50 percent compared to utilization of the polarizer in the illumination path alone.

12. The method of claim 10, wherein a ratio of specularly reflected light intensity from the ocular tear film to background signal intensity is at least 400 percent.

13. The method of claim 1, wherein the background signal includes at least one of stray light and ambient light.

14. The method of claim 1, further comprising displaying the at least one image on a visual display.

15. The method of claim 1, wherein illuminating the ROI of the ocular tear film with a multi-wavelength light source comprises uniformly or substantially uniformly illuminating the ROI of the ocular tear film with a multi-wavelength Lambertian light source.

16. The method of claim 6, wherein the polarizer is a circular polarizer.

17. The method of claim 1, wherein directing the multi-wavelength light including the unpolarized light comprises directing the multi-wavelength light from a light source attached to an imaging platform along an imaging axis and at an illumination angle that is off axis relative to the imaging axis to avoid projecting the multi-wavelength light directly into the pupil of the eye.

18. A method of imaging an ocular tear film, comprising:

directing a light including unpolarized light having a first intensity in an illumination path to illuminate a region of interest (ROI) of an ocular tear film thereby producing a specularly reflected light in a first polarization plane, the specularly reflected light containing optical wave interference from the ROI of the ocular tear film while avoiding projecting the light including the unpolarized light directly into a pupil of an eye;

polarizing the unpolarized light to cause a background signal comprised of unpolarized light returned from the ROI of the ocular tear film to have a second intensity less than the first intensity;

capturing at least one image of the optical wave interference of specularly reflected light and the background signal from the ROI of the ocular tear film; and

receiving the at least one image containing the optical wave interference of specularly reflected light and the background signal.

19. The method of claim 18, wherein reducing the background signal by subtraction is not utilized.

20. The method of claim 18, wherein polarizing attenuates the unpolarized light thereby increasing a ratio of the specularly reflected light to the background signal comprised of the unpolarized light returned from the ROI of the ocular tear film.

21. The method of claim 18, wherein the background signal includes unpolarized light from the ocular tear film comprising at least a portion of the background signal.

22. The method of claim 18, wherein polarizing the unpolarized light decreases intensity of the background signal comprised of the unpolarized light returned from the ROI of the ocular tear film as compared to the intensity of the background signal if a polarizer were not disposed in the illumination path.

23. The method of claim 18, wherein capturing the at least one image of the optical wave interference of specularly reflected light is accomplished by passing the optical wave interference of specularly reflected light through a polarizer disposed in an imaging path of an imaging device.

24. The method of claim 23, wherein the polarizer has a polarization axis aligned parallel or substantially parallel to the specularly reflected light in the first polarization plane from the ROI of the ocular tear film.

25. The method of claim 23, wherein randomly polarized light making up a background signal is reduced by at least 50 percent compared to utilization of the polarizer in the illumination path alone.

26. The method of claim 23, wherein a ratio of specularly reflected light intensity from the ocular tear film to background signal intensity is at least 400 percent.

27. The method of claim 23, wherein illuminating the ROI of the ocular tear film is accomplished by emitting light from a polarized multi-wavelength light source through a polarizer disposed in the illumination path between the polarized multi-wavelength light source and the ocular tear film;

and

wherein capturing the at least one image of the optical wave interference of specularly reflected light is accomplished by passing the optical wave interference of specularly reflected light through a second polarizer disposed in the imaging path of the imaging device.

28. The method of claim 27, wherein randomly polarized light making up a background signal is reduced by at least 50 percent compared to utilization of the polarizer in the illumination path alone.

29. The method of claim 27, wherein a ratio of specularly reflected light intensity from the ocular tear film to background signal intensity is at least 400 percent.

30. The method of claim 18, wherein the background signal includes at least one of stray light and ambient light.

31. The method of claim 18, further comprising displaying the at least one image on a visual display.

32. The method of claim 18, wherein illuminating the ROI of the ocular tear film with a multi-wavelength light source comprises uniformly or substantially uniformly illuminating the ROI of the ocular tear film with a multi-wavelength Lambertian light source.

33. The method of claim 23, wherein the polarizer is a circular polarizer.

34. The method of claim 18, wherein the receiving of the at least one image containing the optical wave interference of specularly reflected light and the background signal occurs while the light including the unpolarized light is being polarized.

35. The method of claim 18, wherein directing the light including the unpolarized light comprises directing the light from a light source attached to an imaging platform along an imaging axis and at an illumination angle that is off axis relative to the imaging axis to avoid projecting the light directly into the pupil of the eye.