I think this is only approved for patients with Retinitis Pigmentosa, where the device attempts to bypass photoreceptors that have long degenerated by stimulating, wirelessly, inner retinal neurons (such as retinal ganglion cells).
You'll find more detailed analysis of 3 patients with the 16-electrode implants in Yanai et al, (2007) Am J Ophth, but they are now trying a 60-electrode design. The more electrodes the better(!), right?