from
http://abcnews.go.com/sections/scitech/CuttingEdge/cuttingedge020329.html


ABCNEWS.com

Orbitz

Sight Chip
A chip designed with multiple layers of cellular nonlinear networks, or CNN,
may lead to an artificial eye that closely mimics the real thing.
(PhotoDisc/ORNL/ABCNEWS.com)
Eyeing a Chip
That Brings Vision
New Chip Design May Lead
to 'Bionic Eye' for the Blind

By Paul Eng
ABCNEWS.com
March 29

- For decades, scientists and eye doctors have been trying to develop
artificial eyes that would return the sense of sight to blind and visually
impaired
people. And the thought of the "bionic eye" may not be too far fetched.

Many companies, such as Optobionics in Wheaton, Ill., have taken the first
steps with tiny microchips that can mimic certain parts and function of the
human
eye - such as the rods and cones, sensors that convert light into electrical
impulses at the retina located at the back of the eye.

But scientists at the Office of Naval Research in Arlington, Va., believe
they are on the path to a chip that could truly mimic the entire nerve
system
of the retina back of the human eye.

At the heart of their potential artificial eye is a well-known chip design
called a cellular nonlinear network, or CNN. In the chip, individual
computer
circuits are connected to each other in a checkerboard array. Each
connection can be given a mathematical "weight" that "describes" the
relationship of
each circuit to each other.

When the chip is exposed to image data, each pixel or point of light in the
picture is sent to a specific cell in the chip. Mathematical algorithms can
then manipulate each connection's weight to produce different resulting
images. One set of algorithms could help find the edges of an object in the
image.
Another set of algorithm could then find corners, while another set define
contours.

Unique Advantages

Larry Cooper, the program manager at Office of Naval Research who
specializes in nanoelectronics, says the CNN chip has multiple advantages
that make it
ideal for use in an artificial retina.

For one, the connections between each circuit are parallel, or "non-linear."
That means, the calculation for each circuit is happening almost
simultaneously
and allows for very rapid image processing. "The time it takes a chip to
[process a function] is about a microsecond," says Cooper.

Another advantage: The chip is an analog processor. Common microprocessors,
such as those used in desktop PC are digital - dealing with values of "1"
and
"0." But the CNN chip can perform its calculations using image values that
aren't as exacting - which is the same way our brain processes information.

Would It Work?

How the CNN chip could be used as an artificial eye, however, is still
fairly theoretical, says Frank Werblin, a professor of neurobiology at the
University
of California at Berkeley.

Werblin, who has conducted his own research in CNN chips, says the ideal use
would be to create a three-dimensional array where each layer of CNNs would
mimic a specific layer of sensors in the human eye. One layer, for example,
would be able to pick out edges, while another picks out color.

And while the algorithms for doing such CNN calculations are well known,
Werblin says the problem is figuring out how to connect it all with the
human brain.
"You have a million optic nerve fibers leaving your eyes, and each goes to
specific part of the brain's cortex," says Werblin. But he says no one knows
just how many or exactly which ones are needed to produce an image that
could be understood by the brain.

Still a Decade Away from Bionic Eyes

And there's still the question of how to connect silicon chips to human
nerve cells - a process that's just being tried out with much simpler chips
such
as Optobionic's artificial light sensors.

David McComb, chief information officer with Optobionics, says the company
has successfully implanted the microchips into the retinas of six patients
under
a clinical trial approved by the Food and Drug Administration. However, actu
al results of how well the chips are working probably won't be released for
review by other scientists until later this year.

And according to both Werlink and Cooper, it will still be quite some time
before CNN chips could be implanted in humans - if ever. Right now, most CNN
chips are just too big - about 1 or 2 square inches - and require too much
power to be embedded in an eye.

Still, the potential prospects of ending blindness through artificial eyes
grows brighter every day.

"Couple of years ago, every one thought this was pie-in-the-sky, Star Wars
stuff," says Dr. Gerald Chader, an opthamologist and chief science officer
for
the Foundation Fighting Blindness. But with more clinical trials and
research, Chader says it's quite possible that some form of chip implants
will be
helping to improving failing eyes in five to 10 years. "In the last couple
of years there has been progress," he says, "We have a great deal of hope
that
there will be positive outcomes."

Copyright © 2002 ABC News Internet Ventures.


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