Google has done a lot of work with contact lenses used in health applications. It’s now patented using a contact lens as an identification device. The patent describes a contact lens that covers all or part of the iris of the eye, and one or more light sensors embedded in the surface of the contact lens collects reflected light off the iris.
The sensors assemble an image of the iris, which is then compared with an image of the same iris contained in computer memory. If the two images match, a door might be unlocked for the wearer, or a file containing privileged information might become accessible, for example.
The patent doesn’t go into specifics about applications for the technology. The lenses, presumably, could be used for biometric authentication purposes within a number of technologies and in various contexts.