Purpose
This study evaluates the Argus™ II Retinal Prosthesis System in blind subjects with severe outer retinal degeneration.
Design
The study design is a single arm, prospective, multicenter clinical trial.
Participants
Thirty subjects were enrolled in the United States and Europe between 6 June 2007 and 11 August 2009. All subjects were followed for a minimum of six months and up to 2.7 years.
Methods
The electronic stimulator and antenna of the implant was sutured onto the sclera using an encircling silicone band. Next, a pars plana vitrectomy was performed and the electrode array and cable were introduced into the eye via a pars plana sclerotomy. The microelectrode array was then tacked to the epiretinal surface.
Main Outcome Measures
The primary safety endpoint for the trial was the number, severity, and relation of adverse events. Principal performance endpoints were assessments of visual function as well as performance on orientation and mobility tasks.
Results
Subjects performed statistically better with system ON vs. OFF in the following tasks: object localization (96% of subjects); motion discrimination (57%); and discrimination of oriented gratings (23%). The best recorded visual acuity to date is 20/1260. Subjects’ mean performance on Orientation and Mobility tasks was significantly better when the System was ON vs. OFF.
Seventy percent of the patients did not have any serious adverse events (SAEs). The most common SAE reported was either conjunctival erosion or dehiscence over the extraocular implant and was successfully treated in all subjects except in one which required explantation of the device without further complications.
Conclusions
The long-term safety results of Second Sight’s retinal prosthesis system are acceptable and the majority of subjects with profound visual loss perform better on visual tasks with system than without.