Argus II retinal implant is safe and 'meaningful' for patients, 5-year results show

The Argus II retinal prosthesis is safe and beneficial for the long-term in patients who are blind due to retinitis pigmentosa (RP), according to 5-year trial results published online July 21, 2016 in the journal Ophthalmology.

“For patients with RP who are living in darkness, the long-term benefits of the Argus II in restoring some useful vision represents a very meaningful milestone,” said lead author Lyndon da Cruz, MD, PhD, Consultant Retinal Surgeon at Moorfields Eye Hospital NHS Foundation Trust, in London, United Kingdom.

Of the 30 patients who began the trial—all of whom had bare light perception vision or worse—24 still had the implant at 5 years. As a single-arm clinical trial in which all subjects had the implant, this study tested patients’ vision with the system turned on vs their residual vision with it turned off.

“Perhaps most exciting is the proven ability of the Argus II to increase patients’ functional vision,” Dr. Cruz said of these tests.

Overall, patients demonstrated better functional vision on computerized and real-life tests with the system turned on. Specifically, 81% of patients were better at locating an object (a white square on a black background), 50% scored better at identifying an object’s direction of motion, and 38% performed grating acuity better with the system on than off, the researchers found. Subjects also performed two “real-world” tests of orientation and mobility: locating and touching a door, and following a white line on the floor.

“With the Argus II, patients can perform tasks that would not be possible without the device. This can be a life-altering change,” Dr. Cruz noted. “It is good that we have now shown that these changes last for many years after implantation.”

In terms of safety, 23 serious adverse events occurred in 12 patients within the first 3 years. One other adverse event, a successfully treated retinal detachment, occurred between years 3 and 5. Two of the implants failed after about 4 years, and 3 patients requested their devices to be explanted between years 3 and 5.

The Argus II is approved in Europe and Canada, and is the only retinal implant approved in the United States, where it is produced by Second Sight Medical Products, of Sylmar, CA. The system consists of a small camera and a video processor, mounted onto a pair of glasses, which converts images into stimulation patterns that are sent to the implanted electrode array on the retina. More than 200 patients worldwide have been implanted with the device, according to the company.

The researchers will continue to follow these 24 patients for up to 10 years in order to obtain even longer-term safety and efficacy data on the implant.