Development of a real-time corneal birefringence compensated glucose sensing polarimeter

Background: As is well known, in order to optimally manage diabetes mellitus, monitoring blood glucose levels several times daily is recommended so appropriate actions can be taken to maintain these levels within a near-normal physiologic range. One technique that shows promise is the use of optical polarimetry. This technique has the potential to noninvasively measure physiological glucose levels in the eye that are correlated to blood glucose concentrations. To date, the main factor limiting in vivo polarimetric glucose measurements is corneal birefringence, which tends to mask the glucose signature. In this investigation, a method to compensate for the effects of corneal birefringence is demonstrated, thus allowing for polarimetric glucose measurements in samples with time-varying birefringence contributions. Methods: In this paper, using a custom-designed laser-based optical polarimetry system with an integrated birefringence compensator, noninvasive glucose measurements in the physiological range are accurately measured within various birefringent samples similar in structure to the eye. Results: Using the laser-based polarimetric approach, it is shown that glucose levels within the physiological range in the presence of significant varying birefringence can be accurately predicted with as low as 13.84 mg/dL error. Conclusions: The ability to compensate for corneal birefringence effects provides promise for the eventual development of a commercial home-based noninvasive polarimetric glucose monitor.