Non-invasive blood glucose monitoring by interferometry
First Claim
1. A method of measuring glucose levels in blood of a living being having an eye comprising a cornea and a lens, which together form an anterior chamber, said eye further comprising an iris and aqueous humor in said anterior chamber, said aqueous humor having an index of refraction correlated to said glucose level in said blood, said method comprising:
- propagating two substantially coherent beams of light through said cornea to illuminate a region of said iris, said two substantially coherent beams of light propagating through said aqueous humor to reach said iris;
overlapping said two beams on said region of said iris, said two beams being sufficiently coherent so as to produce an interference pattern in said region of said iris, said interference pattern comprising a plurality of fringes having a spatial arrangement that depends on said index of refraction of said aqueous humor;
imaging said interference pattern onto a light sensitive optical detector; and
determining said glucose level in said blood from said spatial arrangement of said fringes in said interference pattern.
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Accused Products
Abstract
The glucose concentration in the bloodstream is directly correlated to the concentration of glucose in the aqueous humor. Furthermore, variation in the glucose concentration in the aqueous humor will cause like variations in its index of refraction. Thus, by measuring the refractive index of the aqueous humor, the glucose concentration in the blood can be determined.
The refractive index of the aqueous humor can be measured by interferometry. In various embodiments of the invention that employ interferometry, two beams may be directed onto the eye and caused to interfere, thereby producing a fringe pattern. The fringe pattern may be analyzed to determine the index of refraction of the aqueous humor in the eye and the glucose concentration therein. The glucose level in the blood can be ascertained from this information.
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Citations
26 Claims
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1. A method of measuring glucose levels in blood of a living being having an eye comprising a cornea and a lens, which together form an anterior chamber, said eye further comprising an iris and aqueous humor in said anterior chamber, said aqueous humor having an index of refraction correlated to said glucose level in said blood, said method comprising:
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propagating two substantially coherent beams of light through said cornea to illuminate a region of said iris, said two substantially coherent beams of light propagating through said aqueous humor to reach said iris;
overlapping said two beams on said region of said iris, said two beams being sufficiently coherent so as to produce an interference pattern in said region of said iris, said interference pattern comprising a plurality of fringes having a spatial arrangement that depends on said index of refraction of said aqueous humor;
imaging said interference pattern onto a light sensitive optical detector; and
determining said glucose level in said blood from said spatial arrangement of said fringes in said interference pattern. - View Dependent Claims (2, 3, 4, 5)
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6. An apparatus for monitoring glucose fluctuations by measuring properties of an eye:
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a light source which emits a beam of light;
an optical element situated to receive said beam of light from said light source and to split said beam of light into first and second probe beams that propagate along respective first and second optical paths;
at least one optical element in one of said optical paths to alter said optical path such that first and second probe beams intersect at a target plane; and
an optical detector and imaging optics for imaging said target plane on said optical detector. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of monitoring glucose levels in blood of a living being having an eye, said method comprising:
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propagating light through a portion of said eye comprising aqueous humor having an index of refraction that varies with glucose concentration;
obtaining phase information associated with said light through optical interference, said phase information depending at least in part on said index of refraction of said aqueous humor; and
using said phase information to determine said glucose levels in said blood. - View Dependent Claims (17, 18)
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19. An alignment apparatus for lateral aligning an eye with respect to said apparatus comprising:
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a central light source;
a partially reflecting concave mirror having an optical axis passing therethrough, said central light source centrally disposed along said optical axis such that at least a portion of said light from said central light source propagates through said partially reflecting concave mirror along said optical axis;
first and second offset light sources disposed in a plane passing through said optical axis, said first and second offset light sources on opposite sides of said optical axis, said first and second offset light sources emitting light at an oblique angle toward said optical axis. - View Dependent Claims (20, 21, 22, 23, 24)
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25. A method of aligning a device with respect to a cornea, said cornea having a substantially spherical curvature defined by a center of curvature, said method comprising:
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propagating light toward said cornea, said light having substantially spherical wavefronts defined by a center of curvature that is substantially coincident with said center of curvature of said cornea;
retroreflecting a portion of said light from said cornea;
collecting said retroreflected light; and
focusing said collected light on an optical detector having a photosensitive area such that when said center of curvature of said wavefronts is substantially coincident with said center of curvature of said eye, said light focused on said photosensitive area has a different intensity than when said respective centers of curvature are non-coincident. - View Dependent Claims (26)
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Specification