Patients who are blind from retinitis pigmentosa continue to benefit from a safe retinal implant after 3 years, Ophthalmology reported. Dr Allen Ho and coworkers in the Argus II study group present the complete 1- and 3-year data from the largest, longest-running clinical trial of a retinal prosthesis to date.
The Argus II Retinal Prosthesis System is made up of a device implanted on and in the eye—a receiving antenna, electronics case and intraocular array—and external equipment worn by the user that comprises a glasses-mounted video camera and a small processing unit worn on a shoulder strap or belt.
The device received a CE mark in Europe in 2011 and gained approval from the FDA in 2013.
Profound loss of vision from retinitis pigmentosa, itself a rare disease, is extremely rare, so the trial included only 30 patients. Subjects were recruited at ten centres in the UK, France, Switzerland and the US to have the device implanted in one eye, typically the eye with poorer vision. The system could be turned on or off during assessments, allowing patients to act as their own controls.
Eligible patients, while having bare or no light perception in both eyes, had functional ganglion cells or optic nerve so that the proximal visual system is stimulated when visual data are transmitted from the camera to the array, creating the perception of patterns of light that patients can learn to interpret. They had a previous history of useful form vision.