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Developments in Electronic Vision Systems

Dr. John Gill
April 2002

For many years scientists have addressed the problem of how to use electronic systems to replace some of the functions of the human eye. Up to recently these were just interesting laboratory experiments, but new developments in electronics and wearable computers could turn these prototypes into devices of practical benefit at affordable prices.

The three main approaches are:
· Vision enhancement
· Vision substitution
· Vision replacement

Vision enhancement involves input from a camera, processing of the information, and output on a visual display. In its simplest form it may be a miniature head-mounted camera with the output on a head-mounted visual display (as used in some virtual reality systems).

A more sophisticated system might have a combination of visual and ultrasonic cameras. The ultrasonic camera can provide information about the distance of an object from the camera. The user could then instruct that he or she is only interested in viewing items less than 2 metres away. The processor would then delete all data more than 2 metres; this would significantly reduce the clutter on the visual display.

Another possibility could be that the user is looking for a post box which he knows is painted bright red. He could request that anything which is not red is shown with lower brightness. Yet another possibility is for the user to instruct that only the edges of objects should be displayed. There are many other possibilities for processing the information to meet the specific needs of an individual at that moment.

Vision substitution is similar to vision enhancement but with the output being non-visual - typically tactual or auditory or some combination of the two. Since the senses of touch and hearing have a much lower information capacity than vision, it is essential to process the information to a level that can be handled by the user.

Vision replacement involves displaying the information directly to the visual cortex of the human brain or via the optic nerve.

Vision enhancement systems have already appeared on the market, but significant improvements can be expected in the next few years. Vision substitution systems already exist, mainly as developments of electronic mobility devices, but it is likely to be some years before they come into widespread use. They will need to be accompanied by appropriate training.

Affordable vision replacement systems are farther into the future since much more needs to be known about how to optimally connect to the visual cortex. Since this will involve a surgical procedure, there will need to be stringent testing to ensure that there are no adverse effects.

Over the next few years it will be important to differentiate advertising hype from the real benefits to some people from the appropriate use of these systems. There is a tendency to dismiss developments if they do not live up to the stories in the newspapers, but it would be unwise to dismiss these systems even if claims are made that they "solve the problems of blind people".



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