Bionic eyes
NASA Ames uses nanotechnology in attempts to counteract vision loss
From: Mountain View Voice - 01/03/2003 - page 5
By: Samay Gheewala intern@mv-voice.com

Scientists working on a collaborative effort between the NASA Ames Research
Center and Stanford University Medical Center have made significant gains on
a goal that sounds like something from a science fiction novel.  

They hope to restore sight in patients by implanting a "vision chip" inside
the eye. The chip uses carbon nanotubes (CNTs), or "buckytubes" after their
resemblance to the designs of avantgarde architect Buckminster Fuller, in
place of wires to connect the chip to the patient's own nervous system,
restoring or even improving on the patient's eyesight.  

Potential applications for the technology could be used in fighting disorders
ranging from age-related macular degeneration, the leading cause of vision
loss, all the way to traumatic eye damage. Once the vision chip program is
completed, researchers hope to be able to implant CCD light detectors, like
those used in camcorders and digital cameras, somewhere on the patient, (most
likely within the eye itself), and send the electrical signals generated by
the CCDs through the CNT towers directly to the neural cells within the
retina, through the optic nerve and to the brain.  

While there is along way to go in translating the signals from CCDs into ones
that can be understood by the brain, the team has, made progress in the
growth of CNTs, producing tubes that are up to 100 microns in diameter and
150 microns tall. They hope to be able to dope the CNTs with a variety of
growth factors that wi]l stimulate the attachment of neural cells, making
towers of only 25-50 microns a workable length to connect the neural cells
and the CNT towers. The CNTs have also been proven to have excellent
biocompatibility - they can be implanted in the human body without any immune
reaction or adverse side effects.  

In addition to their advances with the CNTs on their own, the NASA Ames
Vision Chip Program team lead by researcher David J. Loftus has made use of
one of their own developments, a flat membrane composed of interwoven CNTs,
with high porosity and the same tremendous strength inherent in all Bucky
technologies. One of the Vision Chip team's biggest successes involved
successfully implanting a three-millimeter by four-millimeter sheet of Bucky
paper in the eye of a rabbit, without any adverse immunological reactions.
That amount of space would be suitable to support CCDs, CNTs, or even a power
source that would be eventually needed to drive the entire assembly.  

While the researchers are well ahead of their schedule, and appear to have
made amazing strides, they caution that it will still be years before the
necessary CCDs, a way to translate the signals in to something which can be
understood by the brain, and a feasible power source for the system can be
developed. And after that the necessary testing will also take sometime 
before such technology will be ready to give sight to those who cannot see. 

Links:
http://www.scienceblog.com/community/modules.php?name=News&file=print&sid=529