Manufactured by Second Sight Medical Products and co-invented by Mark Humayun of the USC Eye Institute, the Argus II Retinal Prosthesis System was first approved by the U.S. Food and Drug Administration in 2013 to treat adult patients with advanced retinitis pigmentosa (RP); it had been approved in Europe two years earlier.
Retinitis pigmentosa involves a group of inherited conditions characterized by progressive degeneration and dysfunction of the retina. In patients with retinitis pigmentosa, there is a progression loss of night and peripheral vision, leading to a constricted visual field and, sometimes, markedly diminished vision. Several tools are available to help diagnose RP, including full-field electroretinogram, fundus autofluorescence imaging and optical coherence tomography that can identify areas of diseased photoreceptors and guide treatment.
The Argus II system is intended for use in patients with advanced RP. The Argus II relies on a small videocamera attached to sunglasses that sends signals via a video processing unit to an electrode-covered microchip implanted in the back of the eye. The electrodes then transform those signals into electrical impulses that stimulate the retina to produce 60-pixel, black-and-white images, replicating the function of degenerated photoreceptor cells.
Conceptualization of the Argus II began in 1998 following the successful development of the first cochlear implants. Four years later, the first patient received an Argus I implantation. Five additional patients followed. But instead of seeking approval for their initial design, Second Sight focused on the development of a second-generation implant, the Argus II. The first patient received an Argus II in September 2006. Thirty patients with retinitis pigmentosa received the implant as part of the initial clinical trial in Europe and the United States (because the Argus II was designated as a humanitarian use device, it did not need to go through the usual, more rigorous clinical trial process).
Clinical studies have demonstrated the marked impact of the Argus II. Three-year results published in 2015 showed that 30 near-blind patients with advanced RP were able to identify letters and even words successfully with use of the device, and that almost all could more easily perform activities of daily living when the device was turned on. The implanted electrodes have shown good stability beyond 3 years with limited adverse safety concerns.
Approximately 10,000 to 15,000 Americans with retinitis pigmentosa are eligible to receive the Argus II. Through the end of 2014, 100 patients had reported received the Argus II. The device carries a price tag of approximately $150,000.
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