Abstract
Cochlear implants first made their entrance in the late 1970s, and it took about 20 years for them to reach maturity: a device that allows a profoundly, even congenitally, deaf person to hear well enough to converse by phone. Retinal implants have been around for 15 years, but the vision they allow is best described as “moving shadows” and does not allow visual independence to a totally blind person. We will examine 3 shortcomings of current retinal implants: the fundamental reorganization of the degenerated retina, the inability to stimulate at the scale of the target cells, and the need to fine-tune stimulation by recording from the implanted electrodes. We will examine how each of the currently approved implants is positioned to address these shortcomings, and what possible combination of their features could bring us closer to our goal. We will look at the potential benefits and drawbacks of epicortical and intracortical stimulation as the next likely candidates for clinically approved visual prostheses. Finally we will look at the engineering, assessment, and rehabilitation tools we will need to achieve visual prostheses that provide high functionality to the blind.