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Would computerized vision systems work in the congenitally blind?

The headline reads "Computer Helps Blind Man See." It sounds like something directly based on Star Trek's Lieutenant Commander Geordi La Forge, but can it be a step toward a future of treating vision impairment?

The computer system, developed by William Dobelle, of the Dobelle Institute and Columbia-Presbyterian Medical Center in New York, works by stimulating neural noise in the occipital cortex. The occipital cortex is located in the back of the head, and is where vision processing takes place. 'Noise' in the vision system occurs very frequently, and can best be seen when closing your eyes in a dark room. You will notice that what you 'see' is not flat blackness, like a piece of construction paper, but a shifting shimmer of faint geometric patterns. This is a result of random discharge of neural signals from the photoreceptors of the retina, sent to the visual cortex, and interpreted in this way. The computer system stimulates the visual cortex directly, without utilizing the rest of the vision pathway from eyes to optic nerves, to optic chiasm, to optic tracts. This way, individuals with damage to the eye or optic nerve could still have the sensation of sight. The end result is phosphenes…white lights seen on a black background, much like the temperature and time signs outside of banks. Dots of light make up individual shapes in a similar method as pixels on your computer screen. A low number of pixels yields a very grainy, non-detailed image, while higher number of pixels yield greater resolution.

The current system is comprised of a pair of glasses mounted with an ultrasonic distance sensor. A cable runs from the glasses to a computer, roughly the size of a large book, worn on the belt. The computer processes the information and relays it to 68 electrodes implanted directly into the visual cortex. With this system, an individual can make out doorways, very large letters, and gross shapes. All of this is in black and white. At present, only one individual, who lost his vision in adulthood secondary to trauma, is using the system, but more research is underway. Presently, it detects the edges of objects, like a corner or the outline of a letter. Present concepts include taking a digital input directly from a computer or television and inputting it to the visual cortex to allow for computer use.

Would a system like this work in someone who is congenitally blind? Researchers involved are not sure, but physiology of the brain would dictate otherwise. When visual input is never received by the brain, those parts of the brain never 'learn' to see. Most likely, the individual with congenital vision loss would perceive the lights, but not be able to assimilate them into shapes since they have no visual concept of what a shape is. Which will bring us to next month's topic, how does the brain learn to see?

For more information on the Dobelle system, see: Here or here. If you have any comments on this column or topics that you would like to read about in future columns, please email me. Topics addressed in my writings will focus primarily on the latest research in vision care, from how the eye works, to individual diseases, to technological advances, all from a medical/scientific standpoint.

J. Hensil