| Over 25 million people around
the world, including 6 million in the United States, have been visually
affected by genetic retinal diseases. By 2020, that number is expected
to double. But patients who have lost their sight due to genetic eye diseases
that affect the retina may be one step closer to one day regaining some
of their sight.
When patients inherit retinal
diseases, they lose the ability to capture and process the light that passes
through the eye. As these cells degenerate, patients experience vision
loss because they can no longer process light through their photoreceptors.
Researchers at the Doheny Eye Institute at the University of Southern California
(USC) have developed a new prosthetic implant, called the Argus II, that
can better mimic photoreceptor cells in the retina. The new implant,
like its forerunner the Argus I, was developed by Dr. Mark Humayun’s research
team at USC and Second Sight Medical Products Inc, a private company based
in Sylmar, CA. Dr. Humayun, a Professor of Ophthalmology and Biomedical
Engineering at Keck School of Medicine of USC, is the Director of the NSF-funded
Biomimetic Microelectronics Systems Engineering Research Center (BMES)
at USC. BMES is developing the fundamental technology that underpins advanced
neural implants like the retinal prosthesis.
The ARGUS II consists of
a tiny camera and transmitter mounted in eyeglasses, an implanted receiver,
and an electrode-studded array that is secured to the retina with a microtack
the width of a human hair. A wireless microprocessor and battery pack worn
on the belt powers the entire device. It is notable that the microelectronic
circuit that serves as the “brains” of the ARGUS II implant was first developed
with NSF funding, awarded to Humayun and Dr. Wentai Liu, UC Santa Cruz,
between 1998 and 2001. Building on this success, the NSF awarded the BMES
in 2003.
Six patients were implanted
with the ARGUS I beginning in 2002 and can now perceive light, distinguish
between objects, and detect motion. The new implant contains nearly four
times as many electrodes as the original (60 vs. 16), each of which is
independently controllable, allowing patients to process higher-resolution
images. The ARGUS II is also a quarter of the Argus I's size, minimizing
surgery and recovery time. Researchers hope the ARGUS II will be commercially
available in a few years and are currently enrolling subjects in clinical
trials.
The retinal prostheses project
at USC is supported by NSF, the Department of Energy, the National Eye
Institute/NIH, Research to Prevent Blindness, the W.M. Keck Foundation,
and the Albaugh Family Trust
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