Ultrasound gave us our first baby pictures can it also help the blind
see?

Date:
April 12, 2022
Source:
University of Southern California
Summary:
While there are no successful non-invasive therapeutics currently
available for the treatment of vision loss, researchers at have
come up with a new idea to address this growing problem. Currently,
ophthalmologists use electronic technology to directly stimulate
retinal neurons by implanting electrode devices inside the eye, a
technique that requires expensive and invasive surgery. A research
team is now exploring a non-surgical solution that could restore
sight by using another of the five senses: Sound.



FULL STORY ==========================================================================
The number of Americans with visual impairment or blindness is expected
to jump to more than 8 million by the year 2050, according to research led
by the USC Gayle and Edward Roski Eye Institute conducted back in 2016.


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With the youngest baby boomers reaching 65 years old by 2029, age-related
eye diseases and conditions are expected to swell during what's being
called the "silver tsunami." According to medical experts, it's safe to
say many of those cases will be caused by retinal degenerative diseases,
the progressive degeneration of the light-sensitive photoreceptors in
your retina.

Based on these estimates, there is an unmet need for new technologies
that treat vision loss due to diseases of photoreceptor degeneration.

While there are no successful non-invasive therapeutics currently
available for the treatment of vision loss, researchers at USC have come
up with a new idea to address this growing problem.

Currently, ophthalmologists use electronic technology to directly
stimulate retinal neurons by implanting electrode devices inside the eye,
a technique that requires expensive and invasive surgery.



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The research team in the USC Viterbi School of Engineering's Department
of Biomedical Engineering is exploring a non-surgical solution that
could restore sight by using another of the five senses.

Sound.

Ultrasound Technology "This is innovative technology," said Qifa Zhou, professor of biomedical engineering and ophthalmology at USC. "Right
now, we are doing animal studies trying to use ultrasound stimulation to replace electric stimulation." The research group is led by Zhou, and
Mark S. Humayun, professor of ophthalmology and biomedical engineering
at USC, and one of the inventors of Argus II -- the world's first
artificial retina.



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"The technology is advantageous since no surgery is required and no device
will be implanted inside the body," said Gengxi Lu, a Ph.D. student in
Zhou's lab.

"A wearable ultrasound device will generate ultrasound waves to stimulate
the retina." Similar to how shapes and bright spots appear when you
gently push on your eyeball with your eyes closed; researchers realized
that applying pressure to the eye can activate neurons and send signals
to the brain.

Unlike a normal eye that is activated by light, the blind eyes were
stimulated by mechanical pressures generated by ultrasound waves in
this study.

"The neurons present in the retina of the eye possess mechanically
sensitive channels that respond to mechanical stimulation," Lu
explained. "These neurons are activated when we use ultrasound to generate mechanical pressure." How It Works To test this ultrasound approach,
in pre-clinical studies the team at USC stimulated a blind rat's eyes
using high-frequency ultrasound waves that are inaudible to humans.

The technology used in this research is comparable to the ultrasound
probe used for baby imaging that sends and receives sound waves through
a pregnant woman's stomach.

In this case, for retinal stimulation the research group created a small ultrasound device that can be directed at a specific region of the eye to
send sound waves to the retina, which is located in the back of the eye.

Using these high-frequency sounds that can be manipulated and focused
on a specific area of the eye; the study demonstrated that when the
ultrasound waves are projected as a pattern -- for example, the letter
'C' -- the rat's brain was able to pick up a similar pattern.

Unlike in humans, researchers are unable to get direct answers about
the rat's visual experiences during the ultrasound stimulation.

To answer these questions of what exactly the rat was able to visualize
from the ultrasound waves, the team measured visual activity directly
from the rat's visual brain area known as the visual cortex by attaching
a multi-electrode array.

Based on the visual activities recorded from the brain, researchers found
the rat was able to perceive visualizations comparable to the ultrasound stimulation pattern projected to the eye. This work was just published
in BME Fronters (Science Partner Journal).

The Future The research is currently funded by a four-year, $2.3 million
grant from the National Eye Institute (NEI). The team recently applied for another NEI translational grant to take their studies to the next level.

Current studies are conducted mostly using rodent models. However, the
team plans to test this approach using non-human primate models prior
to conducting human clinical trials.

"Right now, we are using a transducer placed in front of the rat's eyeball
to send the ultrasound signals to the retina, but our final goal is to
create a wireless lens transducer" said Dr. Zhou.

While the team is currently analyzing the capabilities of ultrasound
technology for vision study, their future goal is to generate sharper
images and install the ultrasound transducer on a wearable contact lens
for next generation.

There is also a pending patent for this novel ultrasound technology that
hopes to change the way visual impairment is treated years down the road.

Video: https://youtu.be/8JMB6hrZDec

========================================================================== Story Source: Materials provided by
University_of_Southern_California. Original written by Omar Lewis. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Xuejun Qian, Gengxi Lu, Biju B. Thomas, Runze Li, Xiaoyang Chen,
K. Kirk
Shung, Mark Humayun, Qifa Zhou. Noninvasive Ultrasound Retinal
Stimulation for Vision Restoration at High Spatiotemporal
Resolution. BME Frontiers, 2022; 2022: 1 DOI: 10.34133/2022/9829316 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220412095402.htm

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