Evaluation of enzyme-based tear glucose electrochemical sensors over a wide range of blood glucose concentrations.

Miniature enzyme-based amperometric and coulometric glucose sensors were fabricated and applied to measure tear glucose concentrations in anesthetized rabbits. Without perturbing the eyeball, 3 µL of tear fluid was sampled from the marginal conjunctiva under the lower eyelid of anesthetized rabbits at various time points via a microliter glass capillary tube, and the miniature sensors were then inserted into the volume of collected tear fluids within the capillaries for detection. Intravenous bolus doses of insulin were administrated to the rabbits to lower the elevated blood glucose concentrations caused by anesthesia over the 7h test periods. A significant correlation was found between tear and blood glucose levels for multiple rabbits, suggesting that electrochemical sensor-based tear glucose measurements may be a potential supplementary method for point-of-care glucose monitoring.