System and Method for Determining Volume-Related Parameters of Ocular and Other Biological Tissues

• US 20100160789A1
• Filed: 06/18/2009
• Published: 06/24/2010
• Est. Priority Date: 06/18/2008
• Status: Active Grant

• Current Assignee: Eyelab Group, LLC
• Original Assignee: Eyelab Group, LLC
• Inventors: Flanders, Zvi, Cohan, Bruce E., Dilworth, David S., Peshkin, Hannah R.
• Granted Patent: US 9,050,025 B2
• Time in Patent Office: Days
• US Class Current: 600/476
• CPC Class Codes: A61B 3/0025 characterised by electronic signal processing, e.g. eye models
• 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 3/12 for looking at the eye fundus, e.g. ophthalmoscopes A61B3/13 takes precedence
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/1072 measuring distances on the body, e.g. measuring length, height or thickness A61B5/1076 takes precedence
• CPC Class Codes: A61B 5/1079 using optical or photographic means
• CPC Class Codes: A61B 5/7235 Details of waveform analysis A61B5/349 takes precedence

Abstract

A system and method for determining volume-related parameters of a biological tissue, such as ocular tissue, include a light source for projecting light towards the biological tissue, a receiver for receiving light reflected from the biological tissue at two spectral wavelengths, and an image acquisition system in communication with the receiver for forming an image from the reflected light at each wavelength. A processor applies a mathematical model to the image which compares the absorption of light by the biological tissue at a selected image point at each of the two spectral wavelengths to determine the volume-related parameters, such as the relative thickness and material properties, of the biological tissue at that location.

Claims

1. A system for determining volume-related parameters of a biological tissue, comprising:

a light source for projecting light towards the biological tissue;

a receiver for receiving light reflected from the biological tissue at two spectral wavelengths;

an image acquisition system in communication with the receiver for forming an image from the reflected light at each wavelength; and

a processor for applying a mathematical model to the image which compares the absorption of light by the biological tissue at a selected image point at each of the two spectral wavelengths to determine the volume-related parameters of the biological tissue at that location.

2. The system according to claim 1, wherein the biological tissue includes ocular tissue.

3. The system according to claim 1, wherein the model determines the difference between the absorption of light by the biological tissue at the selected image point at each of the two spectral wavelengths to determine a relative thickness of the biological tissue at that location.

4. The system according to claim 3, wherein the model assumes that the absorption of light by the biological tissue is an exponential function of the thickness of the biological tissue.

5. The system according to claim 3, wherein the model normalizes the thickness of the biological tissue to the computed thinnest points of the biological tissue.

6. The system according to claim 1, wherein the model determines the ratio of the absorption of light by the biological tissue at the selected image point at each of the two spectral wavelengths to determine material properties of the biological tissue at that location.

7. The system according to claim 1, further comprising a digitizer in communication with the receiver for digitizing the images formed from the reflected light at each wavelength.

8. The system according to claim 7, wherein the selected image point is a single pixel in the image.

9. The system according to claim 1, further comprising a database for storing images and related data.

10. The system according to claim 1, further comprising a display for displaying the images.

11. A system for determining a relative thickness at a location of an optic disc, comprising:

a light source for projecting light towards the optic disc;

a receiver for receiving light reflected from the optic disc at two spectral wavelengths;

an image acquisition system in communication with the receiver for forming an image from the reflected light at each wavelength; and

a processor for applying a mathematical model to the image which determines the difference between the absorption of light by the optic disc at a selected image point at each of the two spectral wavelengths to determine the relative thickness of the optic disc at that location.

12. The system according to claim 11, wherein the model assumes that the absorption of light by the optic disc is an exponential function of the thickness of the optic disc.

13. The system according to claim 11, wherein the model further determines the ratio of the absorption of light by the optic disc at the selected image point at each of the two spectral wavelengths to determine material properties of the optic disc at that location.

14. A method for determining volume-related parameters of a biological tissue, comprising:

illuminating the biological tissue with light;

receiving light reflected from the biological tissue at two spectral wavelengths;

forming an image from the reflected light at each wavelength; and

applying a mathematical model to the image for comparing the absorption of light by the biological tissue at a selected image point at each of the two spectral wavelengths to determine the volume-related parameters of the biological tissue at that location.

15. The method according to claim 14, wherein the biological tissue includes ocular tissue.

16. The method according to claim 14, wherein comparing the absorption of light includes determining the difference between the absorption of light by the biological tissue at the selected image point at each of the two spectral wavelengths for determining a relative thickness of the biological tissue at that location.

17. The method according to claim 16, wherein determining the relative thickness includes relating the absorption of light by the biological tissue to the thickness of the biological tissue by an exponential function.

18. The method according to claim 16, further comprising normalizing the thickness of the biological tissue to the computed thinnest points of the biological tissue.

19. The method according to claim 14, wherein comparing the absorption of light includes determining the ratio of the absorption of light by the biological tissue at the selected image point at each of the two spectral wavelengths for determining material properties of the biological tissue at that location.

20. The method according to claim 14, further comprising digitizing images formed from the reflected light at each wavelength.

21. The method according to claim 14, wherein the selected image point is a single pixel in the image.

22. The method according to claim 14, further comprising storing images and related data.

23. The method according to claim 22, further comprising comparing the volume-related parameters of the image to other stored images.

24. The method according to claim 14, further comprising obtaining a time series of images of the same biological tissue for comparing the volume-related parameters across multiple images.

25. The method according to claim 14, further comprising generating a grayscale image representing the tissue thickness from the formed image.

26. The method according to claim 25, further comprising generating a three-dimensional rendering combining the formed image and the grayscale image.

27. The method according to claim 14, further comprising identifying fiducial points of interest on the image, finding line segments between distinct features of the image that span the points of interest and the percentage along the line segment of the points of interest, and applying the line segments and percentages to another image to allow location of the points of interest on the other image for comparing the volume-related parameters between the images.

28. The method according to claim 14, further comprising displaying the image.

29. A method for determining a relative thickness at a location of an optic disc, comprising:

illuminating the optic disc with light;

receiving light reflected from the optic disc at two spectral wavelengths;

forming an image from the reflected light at each wavelength; and

applying a mathematical model to the image for determining the difference between the absorption of light by the optic disc at a selected image point at each of the two spectral wavelengths to determine the relative thickness of the optic disc at that location.

30. The method according to claim 29, wherein determining the relative thickness includes relating the absorption of light by the optic disc to the thickness of the optic disc by an exponential function.

31. The method according to claim 29, further comprising determining the ratio of the absorption of light by the optic disc at the selected image point at each of the two spectral wavelengths for determining material properties of the optic disc at that location.

32. The method according to claim 31, further comprising using the determined relative thickness and material properties for assessing a glaucoma condition of the optic disc.

33. The method according to claim 31, further comprising identifying fiducial points of interest on the image, finding line segments between distinct features of the image that span the points of interest and the percentage along the line segment of the points of interest, and applying the line segments and percentages to another image to allow location of the points of interest on the other image for comparing the determined thickness and material properties between the images.

34. The method according to claim 33, wherein the fiducial points of interest are identified on an outer edge of the optic disc.