Retinal Prostheses: Bioengineering Considerations

A typical retinal prosthesis is composed of multiple main functional blocks that operate as an integrated system, including an image acquisition module, an electronics module, and an electrode array. The image acquisition device is responsible for obtaining light information. The images are converted to electrical signals and processed by the electronics module into an electrical stimulation pattern that is applied to the retina through multielectrode array. These three main functional blocks are implemented in a variety of ways. Implementation depends on whether the array is passive (no implanted power source) or active (implanted power source). Another distinguishing design choice of retinal prostheses is the location of electrode array forming a functional interface with retina, which fall into three types: epiretinal (on the top surface of retina), subretinal (between retina and RPE/choroid), and suprachoroidal prostheses (between sclera and choroid). In this chapter, we will review important bioengineering considerations for retinal prostheses.