LEDs Make Better Artificial Eyes

Richard Gaughan

The circumstances surrounding the loss of an eye can be traumatic physically, but the trauma doesn't end there. Besides learning to cope with the loss of a primary sense organ, people also worry about their appearance. An ocular prosthetic, or artificial eye, can create a more natural appearance, but it does not move as the lost eye would. A system under development by researchers in Canada, however, will allow an artificial eye to track the movement of its functioning counterpart.

An eyeglasses-mounted, LED-based tracking system under development by researchers at the University of Alberta and Dalhousie University promises to make artificial eyes look more natural. The system slaves the movement of a servomotor to that of the natural eye.

As a graduate student, Jason Gu built a prototype eye-tracking and rotation-control system with his supervisor, Max Meng, at the University of Alberta. The system uses an array of 950-nm LEDs mounted on the upper part of the frame on a pair of eyeglasses. The light reflects off the surface of the natural eye and to a photodetector array mounted on the lower frame.

As the eye moves, the reflected signal varies. The LED output is modulated to reduce interference from background illumination. By correlating the changes with the motion of the eye, Gu used the photodiode array output to control a 3.5-g servomotor that could move an artificial eye and control its rotation to within 1° of that of the natural eye.

Gu, now an assistant professor at Dalhousie University in Halifax, Nova Scotia, feels that the eyeglasses-mounted approach holds promise. "There are so many methods out there to detect the eye movement," he said. "Our criteria is to get the sensing device reliable, small and energy-efficient."

He said that development of the system is progressing. "We are excited about the potential clinical applications of this work, although we need more funding to speed up and continue."