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M. S. Humayun; Preliminary Results from Argus II Feasibility Study: A 60 Electrode Epiretinal Prosthesis. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4744.
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To provide a clinical update on Second Sight Medical Products Inc., (SSMP) Argus II (A-II) epiretinal prosthesis feasibility study.
So far, seventeen subjects have been implanted at 8 centers. Governmental and institutional approvals were obtained at all centers. All subjects had bare light perception or worse vision due to retinitis pigmentosa (see www.clinicaltrials.gov for more details). The A-II electronics were sutured episcleraly and then after a vitrectomy the electrode array was inserted through the pars plana and tacked to the retina in the macular region. Data from a glasses-mounted camera and power are transmitted wirelessly in real-time to the implant.
The average age of the subjects has been 60 ± 9 years. The median surgical time has been 3:09 hours. All subjects were able to take the system, which included the glasses and battery-operated video processing unit, home for use outside the clinic. Subjects have been implanted an average of 14 ± 6 months. All subjects have reached the 6 month time point which is the data cutoff for this presentation. To date, cumulatively, there have been nearly 20 subject-years of experience with the Argus II implant. The safety of the device has been acceptable and as expected for a new implant design. Most of the major adverse events occurred around the time of surgery (within one month post-operative) and all resolved by the six month endpoint. These major events include conjunctival erosion (n=5 ), hypotony (n=4) and endophthalmitis (n=3). There were no device failures and no explants. On the efficacy side, 100% of the subjects are seeing phosphenes. Significant improvements have also been shown in spatial localization, motion detection, orientation and mobility and other measures. These data will be addressed in detail in this and other presentations at this conference.
With six months follow-up on seventeen subjects, to our knowledge, this is the largest study of a visual prosthesis. The results to date confirm previous reports with the Argus I of phosphene production and the ability of the Argus device to provide visual information with a reasonable safety profile and good reliability.
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