By Edward Chiao
DAILY BRUIN SENIOR STAFF
[email protected]
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UCLA researchers have helped to develop a “vision
chip” which can help some blind patients see again. The
development is good news for one in four Americans over the age of
64, who suffer from a now curable form of blindness according to
the Macular Degeneration Research Foundation. In humans, normal
vision starts when an image passes through the eyeball and into the
retina at the back of the eye. The retina contains photoreceptors
which break down the image and creates the corresponding neural
stimulus, or signals, to the brain. In many blind patients, the
retina degenerates and the photoreceptors no longer function,
leading to blindness. The vision chip works by replacing the
function of the eye’s retina, acting like a photoreceptor
which processes images and sends the correct signals to the brain
to form an image. “In some people, the nerves still work, but
the retina is dead,” said professor Warren Grundfest, chair
of the biomedical engineering department at UCLA. “With this
technology, electrodes are implanted in the back of the
(patient’s) eye, which is controlled by a very complex
system.” The system was developed from research led by Second
Sight, a 4-year old company in Valencia, Calif. It consists of a
tiny video camera mounted onto a pair of glasses to capture images.
These images are then processed by a tiny computer to prepare the
visual information for the prosthetic chip implanted in the
patient’s eye. The signals are then sent via radio
frequencies to the retina chip, which receives the signals (acting
like photoreceptors). The chip finally sends corresponding
electrical pulses through tiny electrodes connected to the chip,
which stimulate neural responses to the brain, forming an image the
blind patient sees. The first such retina prosthesis was implanted
into a patient five months ago at the Retina Institute at USC
Medical Center. “We have been working with the patient to
determine the best way to electrically stimulate his completely
blind retina,” said Dr. Robert Greenberg, President and CEO
of Second Sight. Currently, the vision chip in the patient’s
eye uses a simple two-dimensional 4×4 matrix to simulate vision.
The patient can only see lines and shapes created by the
low-resolution array. “It allows for crude vision such as
identifying orientation of objects and movements,” Greenberg
said. But Greenberg believes higher resolution arrays will help
future patients see with more detail. “A 1,000 electrode
device (30×30 matrix) would provide a level of vision that most of
us would consider adequate for everyday tasks,” Greenberg
said. “Even 100 electrodes would allow the identification of
faces.” Greenberg is working with UCLA electrical engineering
professor Jack Judy on increasing the resolution of the current
low-resolution array. Judy has experimented with micromachining the
electrodes to increase their effective surface areas and reduce
their size on the integrated circuit, allowing for more electrodes
on the chip and better resolution. “The whole concept is the
miniaturization of things,” Judy said. “I’m
focusing on miniaturizing the electrodes on the retina chip but
there are limitations on their size.” In order to stimulate
the neurons in the retina, the electrodes must be able to deliver a
certain amount of current. Decreasing the size of the electrodes
and keeping the current constant will increase the current density.
If the current density increases beyond a threshold density,
electrochemical reactions will occur. “You will have certain
problems (past the threshold current density),” Judy said.
“It can cause hydrolysis (gas bubbles) or even corrode the
metal.” Judy and Greenberg are still experimenting with
several methods to increase the number of electrodes on the chip.
Greenberg is confident they will succeed. “Our effort with
Professor Judy is an important path that may allow such
(high-resolution) arrays,” Greenberg said. “I am sure
we will achieve this goal by one of the methods being
pursued.”
Treatment of Blindness Over Time The work of
researchers at UCLA is part of a long history of education and
advocacy for the blind.
3000 B.C.E. – The Hammurabian Code sets the cost of eye
surgeries at 10 shekels and the punishment for botched operations
as the loss of the surgeon’s hands. 400 – A special hospice
is established specifically for the care of the sightless at
Caesarea in Cappadocia. 1260 – Hundreds of prisoners are blinded by
their captors as a pressure for ransom. In sympathy, King Louis IX
of France sets up an institute for the care of the blind in Paris.
1786 – Valentin Harry writes “An Essay on the Education of
the Blind,” in which he presents the idea of embossing
letters to improve the education of the blind. 1819 – Herr Johann
Wilhelm Klein founds an institute for the blind where dogs are
trained as guides, though his idea does not immediately catch on.
1829 – Louis Braille revises the raised dot system of M. Charles
Barbier to create a more efficient tactile reading and writing
method for the blind. 1911-1918 – Large numbers of German soldiers
are blinded in the first World War. As a result, more attention is
given to training dogs for the blind. 1929 – Morris Frank founds
The Seeing Eye to breed and train dogs as guides for the blind.
1929 – Helen Keller begins work as spokesperson and ambassador for
the American Foundation for the Blind. 1975 – The International
Agency for the Prevention of Blindness, an independent,
nongovernment organization, is founded with the goal of preventing
and curing blindness worldwide. 1978 – The World Health
Organization Programme for the Prevention of the Blind is created
to develop science-based strategies to fight the major causes of
avoidable blindness. Source: American Foundation for the Blind,
World Health Organization, The New York Institute for Special
Education, Association for Guide Dogs.