For diabetics who must check their blood glucose levels regularly, testing can be a nuisance. Between carrying testing equipment, pricking your fingers, and dealing with the sometimes-painful effects of frequent testing, checking your blood glucose level consumes a lot of time. That’s why doctors and diabetic researchers have been working to develop easier, less-invasive testing methods. One of these new methods are contact lenses that help you see more clearly—and monitor your glucose levels.
Although currently unavailable on the open market, researchers are working on creating a version of these lenses that could be mass-produced and sold to diabetes patients everywhere.
There are two types: boronic acid-based lenses and photonic crystals-based lenses. Here’s how they work:
Boronic Acid Contact Lenses
Researchers have developed a form of boronic acid—an acid that is uniquely capable of binding with sugar molecules—which can help measure glucose levels in the fluid of your eyes.
Fluid from the tear ducts contains glucose; molecules in the boronic acid bind with the molecules of sugar in the fluid. The result is fluorescence, which will glow when light from a special hand-held blue light is shown on the eyes. The intensity of the glow lets the wearer measure their blood glucose level. The brighter the fluorescence, the higher the glucose.
Photonic Crystals Contacts
Researchers have also developed contacts using photonic crystals that detect and respond to changes in glucose. Any swings in blood glucose levels are reflected by a change of color in the contacts.
Photonic crystals are made of a combination of boronic acid and other chemicals. These chemicals form long polymer chains, which contain receptors that bind to the structure of glucose. When these chains come into contact with glucose (which is in the fluid of your eye), the spacing and volume are affected, changing how light passes through the material of the contacts. When your glucose is high and the level of glucose in your tears is more concentrated, the polymer chains in your contacts will produce a purple color. When your glucose is low, the lenses will reflect a reddish color. Normal glucose would produce a green color.
These changes in color are on the bottom edge of the lens—in other words, they don’t actually affect the color of your eyes. You would have to look into a mirror and look closely at the lens to see what color is reflected and read your glucose level.
Complications With the Contacts
Unlike the blood in your hands, the tears from your tear ducts do not reflect glucose levels quickly. It takes about 30 minutes for glucose levels in the tears to reach the level in the blood. However, for most people who do pricks every three to four hours, this should not be a problem as the numbers will be close to equal by the time you would be prepared to test again.