Ocular property measuring apparatus and method therefor
First Claim
1. A method of measuring changes in an apparent depth of the anterior chamber of an eye, the anterior chamber being defined by a first interface between the cornea and the aqueous humor of the eye and a second interface between the aqueous humor and the ocular lens of the eye, the method comprising the steps of:
- a) focusing light to a measurement location proximate or within the eye;
b) scanning the measurement location through the anterior chamber;
c) detecting reflected light from the measurement location as the measurement location passes through the first and the second interfaces and generating a signal representative of the detected light;
and using a processor;
d) deriving from the signal apparent positions of the first and the second interfaces and, therefrom, the apparent depth of the anterior chamber;
e) comparing the derived apparent depth with a previous reference measurement of the apparent depth, so as to determine a change in the refractive index of the aqueous humor; and
f) calculating a measure of change in concentration of an analyte of interest in the aqueous humor from the determined change of refractive index.
3 Assignments
0 Petitions
Accused Products
Abstract
A method and apparatus for measuring an apparent depth (1) of a section of an eye (30) are disclosed. Light is focused to a measurement location (15) proximate or within the eye. The measurement location is scanned through the section and upon passing through first and second refractive index interfaces defining the section, a respective reflected light signal is detected, from which apparent positions of the first and second interfaces may be derived. Preferably, a confocal scanning arrangement is employed. Preferably, the section is the aqueous humor (34) of the eye (30). From changes in its refractive index (n) corresponding changes in glucose concentration in the aqueous humor and, in turn, in the bloodstream of a patient may be derived, offering a non-invasive monitoring means for diabetic patients. The apparatus may be a hand-held device, employing microelectromechanical systems. The radius of curvature (R) of a curved section, such as a cornea (32) or ocular lens (36), may also be measured to determine refractive errors of the eye.
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Citations
40 Claims
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1. A method of measuring changes in an apparent depth of the anterior chamber of an eye, the anterior chamber being defined by a first interface between the cornea and the aqueous humor of the eye and a second interface between the aqueous humor and the ocular lens of the eye, the method comprising the steps of:
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a) focusing light to a measurement location proximate or within the eye; b) scanning the measurement location through the anterior chamber; c) detecting reflected light from the measurement location as the measurement location passes through the first and the second interfaces and generating a signal representative of the detected light; and using a processor; d) deriving from the signal apparent positions of the first and the second interfaces and, therefrom, the apparent depth of the anterior chamber; e) comparing the derived apparent depth with a previous reference measurement of the apparent depth, so as to determine a change in the refractive index of the aqueous humor; and f) calculating a measure of change in concentration of an analyte of interest in the aqueous humor from the determined change of refractive index. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An apparatus for measuring changes in an apparent depth of the anterior chamber of an eye, the anterior chamber being defined by a first interface between the cornea and the aqueous humor of the eye and a second interface between the aqueous humor and the ocular lens of the eye, the apparatus comprising:
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a) an optical focusing assembly, adapted to focus incident light to a measurement location proximate or within the eye; b) a scanning assembly, adapted to scan the measurement location through the anterior chamber; c) a detector, adapted to detect reflected light from the measurement location as the measurement location passes through the first and the second interfaces and adapted to generate a signal representative of the detected light; and d) a processor, adapted to; i) derive from the signal apparent positions of the first and the second interfaces and, therefrom, the apparent depth of the anterior chamber; ii) compare the derived apparent depth with a previous reference measurement of the apparent depth, so as to determine a change in the refractive index of the aqueous humor; and iii) calculate a measure of change in concentration of an analyte of interest in the aqueous humor from the determined change of refractive index. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of measuring changes in a property of an eye, comprising the steps of:
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a) directing light from a light source to a first reference location; b) spatially filtering light not received at the first reference location; c) receiving light from the first reference location and focusing the light to a measurement location; d) scanning the measurement location along a measurement line within the eye; e) receiving reflected light from the measurement location and focusing the reflected light to a second reference location; f) spatially filtering reflected light not received at the second reference location; g) measuring an intensity of the reflected light received at the second reference location; and using a processor; h) relating an intensity measurement to an apparent position of the measurement location; i) selecting intensity measurements of interest, the intensity measurements of interest representing measurement locations of interest; and j) deriving a distance between the measurement locations of interest, the distance being an apparent depth of the anterior chamber, the anterior chamber being defined by a first interface between the cornea and the aqueous humor of the eye and a second interface between the aqueous humor and the ocular lens of the eye, the method further comprising the steps of; k) comparing the derived apparent depth with a previous reference measurement of the apparent depth, so as to determine a change in the refractive index of the aqueous humor; and l) calculating a measure of change in concentration of an analyte of interest in the aqueous humor from the determined change of refractive index. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28)
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29. An apparatus for measuring changes in a property of an eye, the property being an apparent depth of the anterior chamber defined by a first interface between the cornea and the aqueous humor of the eye and a second interface between the aqueous humor and the ocular lens of the eye, the apparatus comprising:
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a light source; a source optical element, adapted to direct light from the light source to a first reference location; an objective optical element, adapted to receive light from the first reference location and to focus the light to a measurement location, the objective optical element being further adapted to scan the measurement location along a measurement line within the eye and through the anterior chamber; a return optical element, adapted to receive reflected light from the measurement location and to focus the reflected light to a second reference location; an optical detector, adapted to measure an intensity of the reflected light received at the second reference location; and a processor, adapted to; i) relate intensity measurements of interest to apparent positions of the measurement location, so as to derive the apparent depth of the anterior chamber; ii) compare the derived apparent depth with a previous reference measurement of the apparent depth, so as to determine a change in the refractive index of the aqueous humor; and iii) calculate a measure of change in concentration of an analyte of interest in the aqueous humor from the determined change of refractive index. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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Specification