Epiretinal prosthesis life-changing for some RP patients

Implantation of a retinal prosthesis system (Argus II, Second Sight Medical Systems) in patients with retinitis pigmentosa (RP) is safe and is providing some encouraging results when considered from the recipient’s perspective. Careful patient selection, however, is important and should consider the need for compliance with an intensive postoperative rehabilitation process, said Stanislao Rizzo, MD, at the inaugural Retina World Congress.

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Dr. Rizzo, professor and chairman, Department of Ophthalmology, University of Florence, Italy, reviewed outcomes from the 30 patients with RP he has implanted with the Argus II. He noted that only four (13.3%) severe complications were encountered.

Satisfaction and willingness to undergo the procedure again were investigated in a subgroup of 20 patients who had completed at least 1-year of rehabilitation. Dr. Rizzo described the overall patient satisfaction rating as “very good”-the mean score was 6.8 on a scale of 0 to 10-and three-fourths of the patients said they would have the procedure again.

Strange, difficult surgery

“The implantation of the epiretinal prosthesis is a strange and difficult surgery, although surgical time has decreased from 3.5 hours initially to less than 90 minutes in our last cases, and the implants have all been well-centered on the macula,” Dr. Rizzo said.

“When it comes to outcomes, patient satisfaction is the most important thing," he added. "The majority of our patients said they would have the surgery again and some of those individuals stated ‘the implant changed my life.’

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"Those who said they would not undergo the surgery again commented that they expected more although the limits and benefits of the system had been clearly explained and that the rehabilitation was too demanding," Dr. Rizzo said. "This experience shows that the motivation of the patient and the patient’s relatives are very important.”

The 30 patients in his series ranged in age from 30 to 72 years. The first procedure was done in October 2011, and follow-up for the 30 patients ranges from 4 to 52 months.

The serious adverse events included two cases of choroidal detachment and two cases of retinal detachment with proliferative vitreoretinopathy. The choroidal detachment was secondary to leakage from the sclerotomy, and the two eyes with retinal detachment were lost in follow-up.

Less serious adverse events included retinal schisis that developed in five eyes and a single case of elevated IOP that was controlled medically.

Dr. Rizzo proposed that the retinal schisis develops as a result of fibrosis that develops around the tack, which is used to hold the epiretinal implant, and behind the implant.

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“The implant is still functioning in these eyes, but more energy needs to be applied to elicit visual perception,” he said.

Since its initial introduction, the system has been improved with modifications to the external components, including a more powerful video processing unit and changes to the video camera-bearing eyeglasses that provide improved aesthetics, comfort, usability, and reliability

Beginning in July 2015, Paulo Stanga, MD, began a clinical trial at the Manchester Royal Eye Hospital, Manchester, UK, that is investigating the feasibility of the system in eyes with late-stage dry age-related macular degeneration. In June 2016, Dr. Rizzo implanted the Argus II into a patient with Stargardt's disease.

The system is one of only two epiretinal prostheses that are commercially available. The other device is marketed by Pixium Vision.