Hello Everyone,
I am posting the following article not because it is Apple-related but
because I believe it to be of interest to all of us in this particular
community.
If interested, I strongly recommend that you read the piece in its entirety
as it pertains to all of us, not just those with a particular type of
blindness.
Finally, as this thread is off-topic, I request that no replies be posted,
on-list.
Mark
Blind Patients to Test Bionic Eye Brain Implants, MIT Technology Review.
The maker of the world's first commercial artificial retina, which provides
partial sight to people with a certain form of blindness, is launching a
clinical trial for a brain implant designed to restore vision to more
patients.
The company, Second Sight, is testing whether an array of electrodes placed
on the surface of the brain can return limited vision to people who have
gone partially or completely blind. For decades, scientists have been trying
to develop brain implants to give sight back to the blind but have had
limited success. If the Second Sight device works, it could help millions of
blind patients worldwide, including those who have lost one or both eyes.
The device, called the Orion, is a modified version of the company's current
Argus II bionic eye, which involves a pair of glasses outfitted with a
camera and an external processor. The U.S. Food and Drug Administration has
granted the company a conditional approval for a small study involving five
patients at two sites, Baylor College of Medicine and the University of
California, Los Angeles. Second Sight still needs to conduct further testing
of the device and answer certain questions before starting the trial but
hopes to begin enrolling patients in October and do its first implant by the
end of the year.
Second Sight first won approval in Europe in 2011 for the Argus II, followed
by an FDA approval in 2013 (see "Bionic Eye Implant Approved for U.S.
Patients"). In Europe, two more retinal prosthetics have since been
approved-one is marketed by French company Pixium Vision and another by
German firm Retina Implant.
Also known as a bionic eye, all three devices are intended to bring back
some vision in patients with a genetic eye disorder called retinitis
pigmentosa. The disease causes gradual vision loss when light-sensing cells
called photoreceptors break down in the retina-the tissue membrane that
coats the back of the eye. An estimated 1.5 million people worldwide,
including about 100,000 people in the U.S., have retinitis pigmentosa. That
is a small percentage of the 39 million people worldwide who are blind,
according to the World Health Organization.
A rendering of Second Sight's Orion device, a brain implant that uses most
of the technology from the company's existing device, the Argus II.
But Robert Greenberg, Second Sight's board chair, says the company has only
sold about 250 of the Argus II devices, a number lower than he expected. The
device costs about $150,000 and restores minimal vision. Only 15 centers in
the U.S. offer the technology, and with competition abroad, Second Sight is
hoping its new brain implant could be used by far more pople.
Second Sight's Argus II uses a camera mounted on a pair of glasses to
capture images. The images are sent to a small, patient-worn processor,
which uses special software to convert the images into a set of instructions
that are sent to the implanted chip near the retina. Those instructions are
then transmitted as a series of electrical pulses to an array of electrodes,
also implanted around the eye.
People with retinitis pigmentosa are able to benefit from the device because
the disease destroys only specialized photoreceptors while leaving the
retina's remaining cells intact. These retinal cells are able to transmit
the visual information along the optic nerve to the brain, producing
patterns of light in a patient's field of view.
The new device, the Orion, borrows about 90 percent of its technology from
the Argus II but bypasses the eye. Instead, an array of electrodes is placed
on the surface of the visual cortex, the part of the brain that processes
visual information. Delivering electrical pulses here should tell the brain
to perceive patterns of light.
"In some types of blindness, the optic nerve is damaged so you have to go
downstream. With the Orion, we're essentially replacing the eye and the
optic nerve completely," Greenberg says. With this approach, "anyone who had
vision but has lost it from almost any cause could potentially be helped by
the Orion technology."
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Second Sight estimates that about 400,000 retinitis pigmentosa patients
globally are eligible for its current device, but about 6 million people who
are blind due to other causes, like cancer, diabetic retinopathy, glaucoma,
or trauma could hypothetically use the Orion.
Greenberg hopes the approach will restore the same degree of vision as the
Argus II, possibly a little more. Still, people with bionic eyes have
limited sight. They can distinguish light from dark and recognize the
outlines of objects in their view, but they can't see color. Patient
experiences also vary. Some can read small letters but others can't.
A major downside is the device requires a more invasive surgery than the
Argus II. A small section of the skull needs to be removed to expose the
area of the brain where the array of electrodes is placed. Because
electrical brain implants carry risks like infection or seizures, the first
clinical trial will be small, and the company will start off by testing the
implant in patients who are completely blind.
Last year, Second Sight tried out this approach, implanting an off-the-shelf
neurostimulator device for epilepsy in the brain of a 30-year-old patient
who had been nearly blind for eight years. The patient was able to see spots
of light with no significant adverse side effects.
Researchers at Illinois Institute of Technology in Chicago and Monash
University in Australia are working on similar artificial retinas that would
connect directly to the brain.
Martha Flanders, director of the Central Visual Processing Program at the
National Eye Institute, says a brain implant will be more difficult to get
right than a retinal implant because the brain's visual cortex is so much
more complicated than the eye. Flanders says scientists are still in the
early days of understanding how the brain processes images to produce vision
and how neurons extract information from the visual cortex.
"If we could figure out how to process and filter visual information to
correctly stimulate the electrodes we could eventually improve the type of
image that person will be able to perceive," she says.
Flanders says the Second Sight test is a good first step, but "it's not
going to be like seeing your grandmother."
Because of how complex the brain is, Mark Humayun, a professor of
ophthalmology and biomedical engineering at the University of Southern
California who spent 25 years developing the Argus II, says Second Sight
will need to develop new software and algorithms to convert the visual
information the camera picks up and turns into electrical pulses.
In order to get its new device approved by regulators, Humayun says Second
Sight will need to show that the changes it made are worth the additional
safety risks that come with a more invasive device.
Original Article at:
https://www.technologyreview.com/s/608844/blind-patients-to-test-bionic-eye-
brain-implants/
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