Right now, when you enter a room with low light, the rod cells in your eyes take time to adjust and see clearly. But in red-lit environments, the rod cells send higher contrast images to the brain, making it easier to make out objects. So in dark environments (like a photography room), red lights are often used to improve visibility.
IBM has just patented technology that uses this capability to add night vision capability to Google Glass. According to the IBM’s patent, Google Glass is modified to include a red-color projector for each eyeglass lens.
So when the user enters a low-light environment, the projector automatically projects a low-level red light in to each eye of the user. Shining red light directly into the eyes creates the same response rods as casting red light (from a bulb) onto an environment. Which means it tricks the rod cells into sending higher contrast images to the brain. Giving us all the opportunity to have night-vision goggles.