A patent is thought to have been awarded to Google for a contact lens that can measure glucose levels in tears. The contact lenses have been in Google’s pipeline since before 2014.

The patent details a method of encapsulating a sensor and chip within a polymer (plastic) coating. Whilst this method could convey a number of uses, glucose measuring is certainly one possible and notable use.

Google’s contact lenses have been shown to match the description of the patent in featuring a tiny glucose sensor and chip surrounded either side by the plastic of the lens. The sensor and lens are situated close to the edge of the lens and therefore do not interfere with vision.

How the contact lenses measure sugar levels

The glucose level of tears is generally proportional to the level of glucose within the blood. Blood glucose levels can therefore be determined by applying an algorithm to the glucose level of the tears. The same kind of principle is used by continuous glucose monitors (CGMs), which measure the level of glucose in interstitial fluid rather than directly from the blood.

TIME magazine contacted Google to enquire whether the patent is for glucose level measuring contacts but Google declined to be specific, stating: “We hold patents on a variety of ideas—some of those ideas later mature into real products or services, some don’t.”

Whilst Google have declined to confirm the exact usage of the patent, there is reason to be optimistic. In July 2014, the internet giant announced that it had partnered with pharmaceutical company Novartis to help with licensing and commercializing the glucose level measuring lenses.