Page 45 - T-I JOURNAL19-3

Technology and Innovation, Vol. 19, pp. 605-611, 2018 ISSN 1949-8241 • E-ISSN 1949-825X
Printed in the USA. All rights reserved. http://dx.doi.org/10.21300/19.3.2018.605
Copyright © 2018 National Academy of Inventors. www.technologyandinnovation.org

RETINAL PROSTHESES: THE ARGUS SYSTEM

Tai-Chi Lin 1,2,3,4 , Lan Yue , and Mark S. Humayun 1,2
1,2
1 Department of Ophthalmology, USC Roski Eye Institute, University of Southern California, Los Angeles, CA, USA
USC Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA, USA
2
3 Department of Ophthalmology, Taipei Veterans General Hospital, Taipei, Taiwan, Republic of China
4 Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan, Republic of China

In the late 1990s, Humayun et al. demonstrated intraoperative retinal stimulations from a
multi-electrode array in blind volunteers with little or no light perception. The participants
reported electrically-elicited visual perception in the visual field that corresponded well to
the retinotopic area of stimulation. The subjects exhibited ability to discriminate two separate
stimulation sites and to track perception as the electrode moved across the retina. In another
proof-of-concept trial, Rizzo et al. demonstrated reproducible visual perception with electrical
stimulations of retina in retinitis pigmentosa (RP) patients. With these and other important
pilot studies, two generations of the Argus epiretinal prostheses (Argus I and Argus II), which
function by stimulating the remaining inner retinal neurons in patients with advanced retinal
degeneration, were developed. The basic operations of the Argus series systems are similar,
both consisting of a miniature camera, an external video processing unit, extraocular electron-
ics, and an intraocular electrode array implant. Visual information gathered by the camera is
transformed into controlled patterns of electrical pulses, which are delivered to the surviving
retinal neurons by the electrode array. Results from clinical studies showed that Argus systems
offer opportunities to restore meaningful vision to the patients. In the review, we will focus
on the technical and operational features as well as functional outcomes of the Argus system.

Key words: Argus; Retinal prosthesis; Epiretinal prosthesis; Retinitis pigmentosa

Artificial sight is restoring sight by electrical stim- complex visual processing that occurs downstream
ulation of the visual system. Ancient Greeks were of the retina. As such, the development of cortical
aware of the light perception that is elicited, in the visual prosthesis has been slow to gain more momen-
absence of visual input, by applying mechanical pres- tum. Rather, recent efforts have been largely focused
sure on the eyeball (1). In 1960s, Brindley and Lewin on the development of implants that are placed in
implanted an array of radio receivers connected to proximity of the retina for easier accessibility, lower
electrodes onto the visual cortex of a blind person and surgical risks, well-preserved retinotopic mapping,
showed that short electrical pulses induced sensations and the ability to make use of the remaining retinal
of light in the form of points, spots, and bars of light circuitry for signal processing (3).
(2). However, surgical implantation in the cortex is Although the idea of retinal stimulation was pat-
challenging, and it is difficult to map the visual input ented as early as 1956 (4), it was not until the early
directly to electrical output of the visual cortex due to studies (5,6) demonstrating the feasibility of using
_____________________
Accepted: October 15, 2017.
Address correspondence to Mark S. Humayun, M.D., Ph.D., University of Southern California, 1450 San Pablo Street, Room 6545B, Los Angeles,
California 90033, USA. Tel: +1 (323) 865-3092; Fax: +1 (323) 865-0858. Email: humayun@usc.edu

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