By David Douglas
NEW YORK (Reuters Health) - Post-approval follow-up of the Argus II Retinal Prosthesis System shows safety and visual function outcomes similar to those in previous trials, according to a company-funded study.
With a CE mark granted in 2011, the device became the first retinal prosthesis to be approved for use in Europe.
For the new work, Dr. Jessy D. Dorn of Second Sight Medical Products, in Sylmar, California, and colleagues studied data from nine sites in Italy and Germany. The 47 patients included in the study, most of whom (79%) had retinitis pigmentosa, were followed for at least a year after implantation.
The patients had severe to profound outer retinal degeneration, some residual light perception or the ability of the retina to respond to electrical stimulation. The Argus II captures and processes images from an eyeglass-mounted video camera. These are transmitted to an implant which stimulates the retina via microelectrodes.
During the first 12 months of follow-up, there were 51 adverse events, none of which were serious, the researchers report in JAMA Ophthalmology, online May 30.
However, 12 patients experienced 13 serious adverse events. Nine of these were attributed to the device and four to the implant procedure.
The most common adverse event was conjunctival erosion reported in four patients. Three patients experienced retinal detachment. One underwent explantation because of device failure and another did so because of ocular pain.
The researchers note that no significance testing was done for group analysis of square localization (SL) or direction-of-motion. However, they say, "When averaged across the group, patients' accuracy on the SL test, but not on the direction-of-motion test, appeared better when the Argus II was on than when it was switched off."
In addition, 14 of 30 patients scored 2.9 logMAR or better on grating visual acuity (GVA) with the system on in the implanted eye. None had achieved such a score in the same eye at baseline.
Despite no additional safety concerns having been raised, the investigators conclude that "Longer follow-up with these patients, records from additional patients, and data regarding activities of daily living and quality of life measures are warranted to further enlarge our knowledge on the risk-benefit profile of the Argus II implant."
Dr. Byron L. Lam, co-author of an accompanying editorial, told Reuters Health by email, "The Argus II retinal implant for severe visual loss appears to be safe from the post-approval Germany/Italy Argus II study. The results compare favorably to the previous clinical trial."
Dr. Lam, of the University of Miami Miller School of Medicine, in Florida, added, "More retinal implants and better clinical measures are in the research pipeline."
Ophthalmologist Dr. Andrew Rabinowitz of American Vision Partners in Phoenix, Arizona, told Reuters Health by email, "Methods of improving visual function for those who suffer from catastrophic sight limiting diseases include gene therapy, stem-cell therapy, and most promisingly retinal prostheses. Of these three approaches to sight restoration and maximizing visual function, the Argus II retinal prosthesis is the only one which has shown promise toward achieving is goal."
"The Argus II retinal prosthesis has shown good safety and tolerability in its pre-market studies," said Dr. Rabinowitz, was not involved in the study. "The current, post-market study confirms the safety and efficacy of the Argus II device. The ability to track meaningful functional improvement in daily life with the Argus II warrants additional study."
He noted that "the Argus II retinal prosthesis is the first step toward creating and implanting a retinal implant that can provide meaningful improvement in visual function on a daily basis. There is no doubt that future retinal prostheses will be based upon the insight gained from the Argus II which appears to be the leading approach to sight enhancement in those with severe retinal impairment, especially when compared to the more highly anticipated impact of both gene therapy and stem-cell therapy."
Dr. Dorn did not respond to requests for comments.
SOURCE: https://bit.ly/2WTcezW and https://bit.ly/2Z9SENp
JAMA Ophthalmol 2019.