Diabetes patients need to monitor their blood sugar levels daily. This generally involves pricking their fingers for a blood sample.

Some non-invasive techniques are being developed to monitor blood sugar, but their effectiveness is not yet proven. Google is working on smart contact lens that would be capable of measuring blood sugar.

This will avoid the need for pricking fingers; however, these contact lens will touch human eye, so they are also a bit intrusive.

Now, Xerox has invented an eyeball optical measurement device for measuring characteristics of the aqueous humor in the anterior chamber in an eyeball of a person. 

The device emits light toward an anterior chamber of an eyeball of a person and then detects the light that has passed through aqueous humor in a state that the eyeball is turned outward. The detected light is then analyzed to determine characteristics of the aqueous humor. 

This device exploits the fact that the aqueous humor in the anterior chamber has approximately the same components as blood serum, which contains proteins, glucose, ascorbic acid, etc. It is also well known that there is a correlation between the glucose concentration in blood and that in aqueous humor. Moreover, aqueous humor contains no cellular substances as found in blood and produces only small influences due to light scattering there. The proteins, glucose, ascorbic acid, etc. contained in aqueous humor are optically active substances and have optical rotatory power. Therefore, by measuring a polarization plane rotation angle (optical rotatory power) of optically active substances in the aqueous humor a concentration of glucose can be determined.

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