Psychophysical evaluation for visual prosthesis

Vision restoration through retinal, optic nerve, and cortical implants is no longer just the stuff of fantasy. The design and development of visual prostheses rapidly move from the engineering phase toward preclinical and clinical trials, yet the benchmarks to determine their efficacy in blind research subjects have received very little attention, and likewise the selection criteria and preparation of early recipients of these devices. This article examines the aspects of vision for which prostheses may be of help, the selection of early prosthesis wearers, and the pre- and postimplant evaluations required to assess safety and efficacy. I concentrate on the functional assessment, and particularly on psychophysical methodology, but also address other measures of safety and efficacy, as well as approaches to vision rehabilitation with visual prostheses. Finally, I speculate what roles the first few generations of visual prostheses may play, and emphasize the importance of using simulations to support the development and rehabilitation process.