The Journal of mHealth Vol 1 Issue 2 (Apr 2014) | Page 23

'Bionic Eye' Treatment Paving the Way for Artificial Sight

‘Bionic Eye’ Treatment for
Retinitis Pigmentosa Paving the
Way for Artificial Sight
In January 2014, Second Sight Medical Products Inc. (Second Sight)1
announced that their Argus II Retinal
Prosthesis System had been implanted
in patients with Retinitis Pigmentosa
(RP) for the first time in the United
States. This is a major step forward
for the treatment technology as it is
the first time that the system has been
used on patients with Retinitis Pigmentosa (RP) in the U.S. since it was
approved by the U.S. Food and Drug
Administration (FDA) in 2013.
The procedure which was carried out
at the University of Michigan’s Kellogg Eye Centre by K. Thiran Jayasundera, MD, FRCSC, and David N.
Zacks, MD, PhD, follows the first ever
commercial implant of Argus II which
took place in Italy in 2011. There have
been 18 reimbursed procedures in
Germany and 12 in Italy since then.
Retinitis Pigmentosa (RP) is a rare,
hereditary disease that causes a progressive degeneration of the lightsensitive cells of the retina, leading to
significant visual impairment and ultimately blindness.
Difficulties with night vision and
peripheral vision are the first things
that are noticed. Later, reading vision
(detailed vision), colour vision, and
central vision are affected. The age at
which symptoms start is variable and
the rate of deterioration often differs
between patients - for example with
the different genetic types - but is generally very slow with changes occurring over years rather than months. In
approximately half of all cases there
are other family members with RP.

There are three main inheritance patterns: autosomal recessive, autosomal
dominant and X-linked inheritance;
depending on the genetic cause, with
RP affecting approximately 1 in 3,000
to 4,000 people. There are an estimated 1.2 million people worldwide
with RP.

HOW CAN ARGUS II
REINSTATE SIGHT?
In a healthy eye, the photoreceptors (rods and cones) in the retina convert light into tiny electrochemical impulses that are sent
through the optic nerve and into the
brain, where they are decoded into
images. If the photoreceptors no
longer function correctly—due to
conditions such as retinitis pigmentosa—the first step in this process
is disrupted, and the visual system
cannot transform light into images.
The Argus II Retinal Prosthesis System is designed to bypass the damaged photoreceptors altogether. A
miniature video camera housed in the
patient’s glasses captures a scene. The
video is sent to a small patient-worn

computer (i.e., the video processing
unit – VPU) where it is processed
and transformed into instructions
that are sent back to the glasses via
a cable. These instructions are transmitted wirelessly to an antenna in the
implant. The signals are then sent to
the electrode array, which emits small
pulses of electricity. These pulses are
intended to bypass the damaged photoreceptors and stimulate the retina’s
remaining cells, which transmit the
visual information along the optic
nerve to the brain. This process is
intended to create the perception of
patterns of light which patients can
learn to interpret as visual patterns.
Second Sight gained European
approval (CE Mark) for the system in
2011 and FDA approval in 2013. It is
the first approved retinal prosthesis
anywhere in the world, and the only
such device approved in the USA.
The majority of blind subjects fitted with the Argus II consistently
identify letters and words using the
retinal implant, according to a study
published in the British Journal of
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The Journal of mHealth