Grading corneal fluorescein staining

Patent metadata

Field	Value
Publication number	US-11844571-B2
Application number	US-202217738783-A
Country	US
Kind code	B2
Filing date	May 6, 2022
Priority date	May 2, 2014
Publication date	Dec 19, 2023
Grant date	Dec 19, 2023

Abstract

The technology described in this document can be embodied in systems and computer-implemented methods for determining a score representing an amount of staining of the cornea. The methods include obtaining a digital image of the cornea stained with a tracer material, receiving a selection of a portion of the image, and processing, by a processing device, the selection to exclude areas with one or more artifacts to define an evaluation area. For each of a plurality of pixels within the evaluation area, a plurality of Cartesian color components are determined and a hue value in a polar coordinate based color space is calculated from the components. An amount of staining of the cornea is then determined as a function of the hue value. The methods also include assigning a score to the evaluation area based on the amount of staining calculated for the plurality of pixels.

First claim

What is claimed is:

1. A computer-implemented method comprising:
obtaining a digital image of an ocular surface stained with a tracer material;
defining an evaluation area of the digital image comprising a plurality of pixels by:
dividing the digital image into a plurality of zones, and
excluding one or more zones of the plurality of zones in which a presence of one or more artifacts is detected;

for each pixel of the plurality of pixels:
determining a plurality of color components of a Cartesian color space,
determining, from the plurality of color components, a polar component of a polar coordinate-based color space, and
determining an amount of staining of the ocular surface as a function of the polar component; and

assigning a score to the evaluation area of the digital image based on at least the amount of staining determined for each of the plurality of pixels.

2. The method of claim 1 , wherein the one or more artifacts comprise one of a specular reflection or a confocal reflection.

3. The method of claim 1 , wherein:
the polar component is a first polar component of the polar coordinate-based color space; and
for each pixel of the plurality of pixels, determining the amount of staining further comprises:
mapping an angle corresponding to the first polar component to a scalar value within a range; and
determining the amount of staining as a product of the scalar value and a second component of the polar coordinate-based color space.

4. The method of claim 1 , wherein the tracer material comprises a fluorophore.

5. The method of claim 4 , wherein the fluorophore comprises fluorescein.

6. The method of claim 5 , wherein obtaining the digital image comprises obtaining the digital image in a presence of blue cobalt light.

7. The method of claim 1 , wherein the Cartesian color space is an RGB color space, and wherein the polar coordinate-based color space is an HSV color space.

8. The method of claim 1 , wherein the digital image represents at least part of a cornea.

9. The method of claim 1 , wherein the digital image represents a cornea afflicted with a corneal epithelial disease.

10. The method of claim 1 , wherein the score is indicative of an amount of greenness of the evaluation area.

11. A computer readable storage device having encoded thereon computer readable instructions, which when executed by a processor, cause a processor to perform operations, the operations comprising:
obtaining a digital image of an ocular surface stained with a tracer material;
defining an evaluation area of the digital image comprising a plurality of pixels by:
dividing the digital image into a plurality of zones, and
excluding one or more zones of the plurality of zones in which a presence of one or more artifacts is detected;

for each pixel of the plurality of pixels:
determining a plurality of color components of a Cartesian color space,
determining, from the plurality of color components, a polar component of a polar coordinate-based color space, and
determining an amount of staining of the ocular surface as a function of the polar component; and

assigning a score to the digital image based on at least the amount of staining determined for the plurality of pixels.

12. The computer readable storage device of claim 11 , wherein:
the polar component is a first polar component of the polar coordinate-based color space; and
for each pixel of the plurality of pixels, determining the amount of staining further comprises:
mapping an angle corresponding to the first polar component to a scalar value within a range; and
determining the amount of staining as a product of the scalar value and a second polar component of the polar coordinate-based color space.

13. The computer readable storage device of claim 11 , wherein the digital image represents at least part of a cornea afflicted with a corneal epithelial disease.

14. The computer readable storage device of claim 11 , wherein the tracer material comprises fluorescein, and wherein obtaining the digital image comprises obtaining the digital image in a presence of blue cobalt light.

15. The computer readable storage device of claim 11 , wherein the digital image represents at least part of a cornea.

16. The computer readable storage device of claim 11 , wherein the Cartesian color space is an RGB color space, and the polar coordinate-based color space is an HSV color space.

17. A system comprising:
an imaging system configured to obtain a digital image of an ocular surface stained with a tracer material; and
a score calculator module configured to:
define an evaluation area of the digital image comprising a plurality of pixels by:
dividing the digital image into a plurality of zones, and
excluding one or more zones of the plurality of zones in which a presence of one or more artifacts is detected,

for each of the plurality of pixels:
determining a plurality of color components of a Cartesian color space,
determine, from the plurality of color components, a polar component of a polar coordinate-based color space, and
determine an amount of staining of the ocular surface as a function of the polar component, and

assign a score to the evaluation area of the digital image based on at least the amount of staining determined for each of the plurality of pixels.

18. The system of claim 17 , further comprising a storage device configured to store the score and an association of the score with the digital image.

19. The system of claim 17 , wherein the tracer material is a fluorophore that includes fluorescein.

20. The system of claim 17 , wherein the imaging system further comprises a light source for radiating blue cobalt light to illuminate the ocular surface.

Assignees

• Massachusetts Eye & Ear Infirmary

Inventors

• Dana Reza
• Amparo Pulido Francisco L
• Wang Haobing

Classifications

• A61B3/0025 Primary

  characterised by electronic signal processing, e.g. eye models · CPC title

• A61B5/0071

  by measuring fluorescence emission · CPC title

• A61B5/1032

  Determining colour of tissue for diagnostic purposes · CPC title

• A61B5/4848

  Monitoring or testing the effects of treatment, e.g. of medication · CPC title

• A61B3/1025

  for confocal scanning · CPC title