Ocular Property Measuring Apparatus for Non-Invasive Glucose Monitoring
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Solution Overview
Problem
Current non-invasive methods for measuring blood glucose levels through the eye are prone to inaccuracies due to factors like stray light, diurnal variations, and changes in the cornea and tear film, making them unsuitable for reliable, portable, and cost-effective solutions.
Innovation Solution
A method and apparatus that measure changes in the apparent depth of the anterior chamber of the eye by focusing light, scanning through the chamber, detecting reflected light, and calculating changes in refractive index to determine glucose concentration in the aqueous humor, which can be used to infer blood glucose levels, without requiring a laser and being less affected by external conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If reflectometry is used to measure glucose concentration in aqueous humor, then non-invasive measurement is achieved, but measurement precision deteriorates due to stray light and corneal changes
Solution Approach 1:
The measurement is divided into two separate parts: first measuring the optical properties of the cornea, then measuring the combined optical properties of the cornea and aqueous humor. By segmenting the measurement process, the patent can isolate and subtract the corneal contribution to obtain accurate aqueous humor properties without being affected by stray light or corneal changes.
Solution Approach 2:
The patent performs measurements at multiple wavelengths (excessive action) to obtain sufficient data for calculating both corneal and aqueous humor optical properties. By using more measurement data points than the minimum required, the system can accurately separate the contributions of different ocular structures and compensate for variations.
2Measurement precision
If interferometry with laser is used to measure refractive index of aqueous humor, then measurement precision is improved, but device complexity increases and portability is reduced
Solution Approach 1:
The patent replaces complex mechanical interferometric systems with a simplified optical measurement system using LED light sources and photodetectors. By substituting mechanical precision components with more robust optical elements, the system achieves comparable measurement precision while dramatically reducing device complexity and enabling portability.
Solution Approach 2:
The patent changes the measurement parameters by using multiple wavelengths of light and measuring optical properties at different spectral points. This parameter change allows the system to calculate refractive index through mathematical analysis rather than requiring complex interferometric hardware, thus simplifying the device while maintaining precision.
3Measurement precision
If blood sampling method is used to measure glucose concentration, then measurement precision is improved, but ease of operation deteriorates due to invasiveness and discomfort
Solution Approach 1:
The patent uses the aqueous humor as an intermediary medium to indirectly measure blood glucose concentration. Instead of directly sampling blood, the system measures the optical properties of the aqueous humor, which contains glucose that correlates with blood glucose levels. This intermediary approach eliminates the need for invasive blood sampling while maintaining measurement accuracy.
4Measurement precision
If spectrometry is used to measure glucose in aqueous humor, then measurement precision is improved, but use of energy increases due to laser requirements
Solution Approach 1:
The patent replaces expensive, high-energy laser sources with inexpensive LED light sources that consume significantly less energy. By using LEDs that emit at multiple wavelengths and can be easily filtered, the system achieves comparable spectral measurement capabilities with much lower energy consumption, making the device suitable for portable and frequent use.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides high axial resolution, is less affected by atmospheric conditions, allows for deconvolution of corneal changes, and can be used in a compact, portable device, enabling reliable and frequent monitoring of blood glucose levels.
Implementation Method 1
a light source adapted to project light through a pinhole aperture to a measurement location
Implementation Method 2
a lens arrangement, the focal point of which is scanned from a position in front of the cornea to a position behind the ocular lens
Implementation Method 3
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
Implementation Method 4
deriving from the signal apparent positions of the first and the second interfaces and, therefrom, the apparent depth of the anterior chamber; 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
Data Source
AI summary
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.