Ocular surface interferometry (OSI) methods for imaging, processing, and/or displaying an ocular tear film

• US 8,545,017 B2
• Filed: 04/01/2010
• Issued: 10/01/2013
• 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): HASAN, MOHAMMED A
• Application Number:
  US12/798,325
• Publication Number:
  US 20100259722A1
• Time in Patent Office: 1,279 Days
• Field of Search: 351200-246
• US Class Current: 351/206
• 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

Ocular surface interferometry (OSI) devices, systems, and methods 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). The measured TFLT can be used to 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 a first image. The imaging device can also be focused on the lipid layer of the tear film to capture a second image containing the background signal(s) present in the first image. The second image can be subtracted from the first image to reduce and/or eliminate the background signal(s) in the first image to produce a resulting image. The resulting 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:

illuminating a region of interest of the ocular tear film with a multi-wavelength light source;

capturing optical wave interference of specularly reflected light including a background signal from the region of interest of the ocular tear film while illuminated by the multi-wavelength light source in at least one first image by an imaging device;

capturing only the background signal from the region of interest of the ocular tear film in at least one second image by the imaging device; and

subtracting the at least one second image from the at least one first image to generate at least one resulting image containing the optical wave interference of specularly reflected light from the region of interest of the ocular tear film with the background signal removed or reduced.

2. The method of claim 1, wherein the optical wave interference of specularly reflected light from the ocular tear film is comprised of one or more optical wave interference signals.

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

4. The method of claim 1, comprising capturing the at least one second image when the multi-wavelength light source is not illuminating the region of interest of the ocular tear film.

5. The method of claim 1, comprising capturing the at least one second image when the multi-wavelength light source is illuminating the region of interest of the ocular tear film.

6. The method of claim 5, wherein the background signal includes diffusely reflected light resulting from illumination of the ocular tear film.

7. The method of claim 6, wherein the background signal includes diffusely reflected light from an iris of an eye.

8. The method of claim 5, wherein capturing the background signal from the region of interest of the ocular tear film in at least one second image further comprises not capturing specularly reflected light from the region of interest of the ocular tear film.

9. The method of claim 1, wherein illuminating the region of interest of the ocular tear film with the multi-wavelength light source comprises controlling the multi-wavelength light source to produce specularly reflected light from at least one first portion of the region of interest of the ocular tear film while obliquely illuminating at least one second portion of the region of interest of the ocular tear film adjacent to the at least one first portion.

10. The method of claim 9, further comprising controlling the multi-wavelength light source to produce specularly reflected light from the at least one second portion of the region of interest of the ocular tear film while obliquely illuminating the at least one first portion of the region of interest of the ocular tear film adjacent to the at least one second portion.

11. The method of claim 10, wherein capturing the optical wave interference of specularly reflected light including the background signal from the region of interest comprises:

capturing a first tiled pattern of the specularly reflected light including the background signal from the at least one first portion of the region of interest of the ocular tear film in the at least one first image by the imaging device; and

capturing a second tiled pattern of the specularly reflected light including the background signal from at least one second portion of the region of interest of the ocular tear film in the at least one second image by the imaging device.

12. The method of claim 11, wherein capturing the background signal from the region of interest of the ocular tear film comprises:

capturing the background signal from the at least one second portion of the region of interest in the first tiled pattern in the at least one first image; and

capturing the background signal from the least one first portion of the region of interest in the second tiled pattern in the at least one second image.

13. The method of claim 12, wherein the at least one first portion and the at least one second portion are located adjacent to each other.

14. The method of claim 12, further comprising combining the at least one first image to the at least one second image to form the at least one resulting image in a tiled pattern containing the optical wave interference of specularly reflected light from the region of interest of the ocular tear film with the background signal removed or reduced.

15. The method of claim 11, wherein the first tiled pattern is comprised from the group consisting of teeth patterns and a plurality of concentric patterns.

16. The method of claim 11, wherein the at least one first portion and the at least one second portion are comprised of equal or approximately equal areas.

17. The method of claim 1, further comprising sequentially repeating the capturing of the optical wave interference of specularly reflected light and the background signal in the at least one first image to provide a plurality of first images, and the capturing of the background signal in the at least one second image to provide a plurality of second images interleaved with the plurality of first images to provide a plurality of first and second image pairs.

18. The method of claim 17, wherein the subtracting is comprised of subtracting the second images from the plurality of first and second image pairs from the corresponding first images from the plurality of first and second image pairs to generate a plurality of resulting images each containing the optical wave interference of specularly reflected light from the region of interest of the ocular tear film with the background signal removed or reduced.

19. The method of claim 1, further comprising setting a linear response on the imaging device.

20. The method of claim 19, wherein setting the linear response comprises adjusting a gamma correction of the imaging device.

21. The method of claim 1, further comprising synchronizing the illumination of the region of interest of the ocular tear film with obtaining the at least one first image.

22. The method of claim 1, further comprising selectively controlling one or more light emissions devices within the multi-wavelength light source when illuminating the region of interest of the ocular tear film.

23. The method of claim 1, further comprising positioning at least one of the multi-wavelength light source and the imaging device relevant to the ocular tear film prior to capturing the at least one first image and capturing the at least one second image.

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

25. The method of claim 1, further comprising displaying at least one of the at least one first image, the at least one second image, or the at least one resulting image on a visual display.

26. The method of claim 25, further comprising adjusting a linearity of the at least one resulting image before displaying the at least one resulting image on the visual display.

27. The method of claim 1, further comprising displaying the resulting image overlaid onto at least one of the at least one first image and the at least one second image on a visual display.

28. The method of claim 25, further comprising adjusting either a contrast level, a saturation level, or both the contrast and the saturation level of the at least one resulting image displayed on the visual display.

29. The method of claim 13, wherein the at least one first portion is comprised of a plurality of first portions of the region of interest, and the at least one second portion is comprised of a plurality of second portions of the region of interest.