Digital controllers Controllers 5 Field programmable gate arrays (FPGA) 5 Implants (surgical) 5 Ophthalmology 5 Controlled drug delivery 3 Cost effectiveness 3 Digital controller designs 3 Field programmables 3 Field-programmable gated array 3 Hexagonal stimulation 3 Implant devices 3 Integrated circuit design 3 Micro/nano 3 Retinal implant technology 3 Subretinal implants 3 Wireless telemetry systems 3 digital controller 3 field-programmable gated arrays 3 hexagonal stimulation 3 wireless telemetry system 3 Back telemetry 2 Control unit 2 Digital power controller 2 Energy efficiency 2 Implantable medical devices 2 Power amplifiers 2 Power control 2 Power controllers 2 Power efficient 2