Multispectral and hyperspectral ocular surface evaluator
View Patent ↗A multispectral or hyperspectral ocular surface evaluating device is disclosed, comprising an illumination projector, which comprises a broadband illumination source panel and a polarizing structure to illuminate an ocular surface and adjacent structures of an eye and project a pattern on the ocular surface; an imaging system to form images; a detection system to record the images with a plurality of spectral channels in visible and near infrared spectra; and a computer to display and analyze the images. Also disclosed is a method of evaluating ocular surface health using a multispectral or hyperspectral ocular surface evaluating device, which comprises illuminating an ocular surface and adjacent structures of an eye with polarized light from an illumination projector; forming images with the imaging system; recording images formed on the detection system; digitally processing the recorded images; and analyzing the recorded images to evaluate ocular surface health with the computer.
1. A multispectral or hyperspectral ocular surface evaluating device, said device comprising:
an illumination projector with an aperture in a posterior end of said projector, wherein said illumination projector comprises a broadband illumination source panel and a polarizing structure to illuminate an ocular surface and adjacent structures of an eye and project a pattern on said ocular surface, wherein said broadband illumination source panel covers visible and near infrared spectra;
an imaging system to form images of said ocular surface and adjacent structures;
a detection system to record said images with a plurality of spectral channels in visible and near infrared spectra using spectral filters or dispersive optical elements; and
a computer to display and analyze said images.
2. The apparatus of claim 1 , wherein said illumination projector has a shape of rotational symmetry, wherein said illumination projector comprises:
a broadband illumination source panel with visible and near infrared light-emitting diodes (LEDs);
a diffusing structure with one or more layers of translucent materials;
a projection pattern panel; and
a polarizing structure to control a polarization state distribution of incident light on said ocular surface and adjacent structures.
3. The apparatus of claim 1 , wherein said polarizing structure of said illumination projector comprises a member selected from a group consisting of a linear polarizer, a circular polarizer, an elliptical polarizer, a variable polarizer, a sectional polarizing structure with different sections of different polarizing properties, and a combination of a linear polarizer and two high order retarders.
4. The apparatus of claim 1 , further comprising:
a polarization analyzing structure placed in either said imaging system or said detection system.
5. The apparatus of claim 4 , wherein said polarization analyzing structure comprises a member selected from a group consisting of a linear polarizer, a circular analyzer, an elliptical analyzer, a rotating polarizer, a variable analyzer, a combination of two high order retarders and a linear polarizer, and a combination of a first Savart plates, a half wave plate, a second Savart plate, and a linear polarizer.
6. The apparatus of claim 1 , further comprising:
an eye alignment system to provide a fixation target for an eye under assessment, wherein said eye alignment system comprises a light source and a beamsplitter, wherein said eye alignment system and said imaging system are aligned coaxially.
7. The apparatus of claim 1 , wherein said imaging system comprises a member selected from a group consisting of a fixed focal lens group, a lens group with a magnification changer, and a zoom lens group.
8. The apparatus of claim 1 , wherein said detection system is a multispectral detection system, wherein said multispectral detection system comprises a member selected from a group consisting of a detector sensitive to visible and near infrared spectra, a detector with alternating spectral filters, and a combination of detectors and dichroic beamsplitters.
9. The apparatus of claim 1 , wherein said detection system is a hyperspectral detection system, wherein said hyperspectral detection system comprises a member selected from a group consisting of a spectrometer system, a snapshot imaging spectrometer system, and a spectral scanning detector.
10. The apparatus of claim 1 , wherein a thermal camera is placed paraxially with said imaging system to measure a dynamical thermal change of said ocular surface.
11. The apparatus of claim 1 , wherein a retinal polarimeter is added, wherein said retinal polarimeter comprises retinal illumination optics and a compensating lens group.
12. A method of evaluating ocular surface health using a multispectral or hyperspectral ocular surface evaluating device according to claim 1 , comprising:
illuminating an ocular surface and adjacent structures of an eye with polarized light from an illumination projector, covering visible and near infrared spectra;
forming images of said ocular surface and adjacent structures of said eye with said imaging system;
recording images formed on said detection system;
digitally processing said recorded images to obtain spatial and spectral information; and
analyzing said recorded images to evaluate ocular surface health with said computer.
13. The method of claim 12 , wherein said digital processing comprises:
image preprocessing;
feature extraction; and
parameter estimation, wherein characterization parameters of said ocular surface and adjacent structures are estimated.
14. The method of claim 13 , wherein said parameter estimation comprises a multi layer model of said ocular surface and adjacent structures, wherein each layer is modeled by said characterization parameters, wherein an inverse model based on a parametric method or a machine learning method is used for said parameter estimation.
15. The method of claim 12 , wherein analyzing comprises analyzing reflected images of said illumination projector off said ocular surface to determine a topography of said ocular surface.
16. The method of claim 12 , wherein analyzing comprises evaluating a time interval between a last blink and an occurrence of a disrupted area of a pattern of reflected images of said illumination projector off said ocular surface to determine a tear breakup time.
17. The method of claim 12 , wherein said analyzing comprises inspecting ocular features with said plurality of spectral channels of said detection system, wherein said ocular features comprises a member selected from a group consisting of tear meniscus height, bases of eyelashes, meibomian gland orifices, and meibomian glands of an everted eyelid.
18. The method of claim 12 , wherein said analyzing comprises quantitatively evaluating a bulbar redness and a palpebral redness of the eye based on a conjunctival vascular distribution.
19. The method of claim 12 , wherein said analyzing comprises determining lipid layer thickness by polarimetric reflectance values in said plurality of spectral channels of said detection system.
20. The method of claim 12 , wherein said analyzing comprises determining corneal birefringence.