Artificial Vision System Can Aid Blind.

• Position: Brief Article

A biomedical engineering team has announced development of an artificial vision system providing independent mobility to blind people. Reflecting more than 30 years in development by the Dobelle Institute in New York and its affiliates in Switzerland, it enables a totally blind person to achieve visual acuity of about 20/400, in a narrow visual "tunnel."

The "Dobelle Eye" consists of a sub-miniature television camera and an ultrasonic distance sensor, both mounted on a pair of eyeglasses. The sensors connect through a cable to a miniature computer worn in a pack on a person's belt. After processing the video and distance signals, it uses sophisticated computer-imaging technology, including edge-detection algorithms, to simplify the image, eliminating "noise." The computer then triggers a second microcomputer that transmits pulses to an array of 68 platinum electrodes which are implanted on the surface of the brain's visual cortex.

When stimulated, each electrode produces up to four closely spaced phosphenes, which have been described as resembling "stars in the sky." This white phosphene on a black background "map" is roughly eight inches by two inches at arms length.

The patient in the study is a 62-year-old man who was totally blinded by trauma when he was 36 years old. After being taught to use the system and "read" the display, he is able to decipher two-inch tall letters at a distance of five feet. Although the relatively small electrode array produces tunnel vision, the patient is able to navigate in...