Several companies are developing prototypes for heads-up display attachments to eyeglasses — the wearer can look through them and see the real world with an overlay image presenting virtual information.

The technology uses “holographic optics”: light-emitting laser diodes in the side of the frame, shoot highly concentrated beams forward to the eyeglass surface. There, computerized, transparent devices called holographic gratings diffract light, steering it to the user’s eyes.

University of Washington and Microsoft researchers have also created a biocompatible contact lens that has miniaturized electronics and optoelectronics integrated into the lens.