Making the Blind to See

A biomedical engineering team has developed an artificial vision system that can provide mobility to blind people. The system, more than 30 years in the making at the Dobelle Institute in New York City and its affiliates on Long Island and in Switzerland, enables a totally blind person to achieve visual acuity of about 20/400 in a narrow visual "tunnel."

The "Dobelle Eye," described in the current issue of the Journal of the American Society of Artificial Internal Organs (ASAIO), consists of a tiny television camera and an ultrasonic distance sensor, both mounted on a pair of eyeglasses. The sensors are connected through a cable to a small computer, worn in a belt-pack. After processing the video and distance signals, the computer uses edge-detection algorithms to simplify the image, and then transmits pulses to an array of 68 platinum electrodes implanted on the surface of the brain's visual cortex.

When stimulated, each electrode produces one to four closely spaced phosphenes, which resemble "stars in the sky." This white phosphene on a black background "map" is roughly eight inches by two inches at arm's length.

The patient in the study reported in ASAIO Journal is a 62-year-old male who lost his vision at age 36 by a blow to the head. After learning to "read" the display, he can now read two-inch tall letters at a distance of five feet. Although the small electrode array produces tunnel vision, the patient can navigate even in unfamiliar environments. By replacing the sub-miniature television camera with a special electronic interface, the patient is also learning to "watch" television, use a computer, and gain access to the Internet.

Blind volunteer with sub-miniature TV camera mounted on the right lens of his sunglasses, and the laser-pointer (position monitor) on the left temple piece.

The original package employed a 2,000-pound computer the size of a large bookcase and weighed several thousand pounds. After six generations of improvement, taking some 20 years, the external electronics package has been reduced to the size of a dictionary and weighs approximately ten pounds, including batteries.

Dobelle said that the new artificial vision systems are expected to be made available on a limited commercial basis, starting later this year.

For more information: W.H. Dobelle, Dobelle Institute Inc., Columbia-Presbyterian Medical Center, New York, NY 10032.

Edited by Laura DeFrancesco