Table 1:

Summary of Optoelectronic Devices

Device:	Type:	How it works:	Benefits:	Limitations:
ARGUS II Source: Courtesy of SecondSight	Epiretinal implant with external camera	External camera records and transmits pulses wirelessly through microelectrode array to inner retina	Unaffected by corneal or lens opacities due to wireless transmission from camera to array; long-term safety has been demonstrated	Visual perception through fixed camera is independent of eye movement; 60 electrodes limits potential visual acuity
IRIS II Source: Courtesy of Pixium Vision	Epiretinal implant with external camera	External camera records and transmits pulses wirelessly through microelectrode array to inner retina	Exchangeable system allows for replacement; unaffected by corneal or lens opacities due to wireless transmission from camera to array	Visual perception through fixed camera is independent of eye movement; 150 electrodes but requires further studies to demonstrate efficacy
Alpha IMS/AMS (Discontinued) Source: Retina Implant AG, Reutlingen, Germany, used by Bloch et al. 2019, licensed under CC-NY.	Subretinal implant	Photodiode array in subretinal space that detects light and converts it to electrical signals transmitted to overlying retina	Vision generated corresponds with natural eye movement due to subretinal implant itself directly detecting light	Affected by opacities between cornea and retina due to requiring light to reach the retina; 1500 (IMS) or 1600 (AMS) electrodes but visual acuity significantly below potential
PRIMA Source: Courtesy of Pixium Vision	Subretinal implant with external camera	External camera records video that is processed and projected via infrared laser patterns through the pupil to subretinal implant, where photovoltaic array converts the light to electrical signals stimulating bipolar cells	Design of subretinal implant includes ground grid around each stimulating electrode allowing theoretical improvement of resolution	Affected by opacities between cornea and retina due to requiring light to reach the retina; 378 pixels (electrodes) but requires clinical trials to demonstrate efficacy
Bionic Vision Australia Source: Courtesy of Ayton et al. 2014, originally from Bionic Vision Technologies	Suprachoroidal implant with external camera	External camera records and transmits pulses wirelessly through microelectrode array through choroid to inner retina	Unaffected by corneal or lens opacities due to wireless transmission from camera to array	Visual perception through fixed camera is independent of eye movement; 44 channels (electrodes) limits potential visual acuity and requires clinical trials to demonstrate efficacy
Orion Cortical Implant Source: Courtesy of SecondSight	Cortical implant with external camera	External camera records and transmits pulses wirelessly to microelectrode array to medial occipital lobe	Unaffected by corneal or lens opacities due to wireless transmission from camera to array; potential for use in patients with significant inner retina and/or optic nerve degeneration	Visual perception through fixed camera is independent of eye movement; 60 electrodes limits potential visual acuity; requires clinical trials to demonstrate efficacy and long-term safety