Retinal prosthesis safety, performance positive years after implantation

New Orleans-Findings from an international trial with follow-up in some subjects now extending beyond 6 years show that a retinal prosthesis (Argus II Retinal Prosthesis System, Second Sight Medical Products) remains safe, said Allen C. Ho, MD.

The system also continues to be reliable, and provides patients with durable visual function benefits that allow improved performance of visual functional tasks and increased well-being, said Dr. Ho, an investigator in the clinical trial.

The prosthesis was approved for patients with late-stage retinitis pigmentosa (RP) by the FDA in February 2013.

“The [system] represents a major biomedical advance for those afflicted with severe blinding retinal degenerations,” said Dr. Ho, professor of ophthalmology, Thomas Jefferson University, and the Wills Eye Hospital Director of Retina Research, Philadelphia, as well as an investigator in the clinical trial.

It literally enables the blind to see in a way that reconnects them to a visual world that is meaningful and improves their quality of life, he said.

“The ability to sort dark and white laundry may seem mundane to many of us, but it is monumental for patients who before they had this prosthesis surgery lived in a world of only darkness,” Dr. Ho said.

The study enrolled 30 patients at 10 centers in the United States, the United Kingdom, France, and Switzerland.

The patients had severe to profound outer retinal degeneration secondary to retinitis pigmentosa (29 eyes) or choroideremia (1 eye) with visual acuity worse than 2.3 logMAR in both eyes. Visual acuity was bare light perception in 29 patients and no light perception in 1 individual.

Minimum follow-up for the cohort is 4.8 years, and cumulative subject-years of follow-up exceed 140 years.

During this period, the epiretinal electrode array was explanted in three patients, of whom one experienced recurrent conjunctival erosion and two chose to have the system removed.

Communication failure with the implant occurred at 4 years postoperatively in two other patients who have not undergone epiretinal electrode array explantation. There were no other reliability issues.

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