gms | German Medical Science

Degenerative diseases such as age-related macular degeneration (AMD) and retinitis pigmentosa (RP) primarily affect the photoreceptors, ultimately resulting in significant loss of vision. Retinal prostheses aim to elicit neural activity in the remaining retinal cells by detecting and converting light into electrical stimuli that can then be delivered to the retina, either through and epiretinal or subretinal stimulator.

The results of clinically used systems are quite equivalent, helping blind patients in mobility and orientation.

Main advantage of epiretinal stimulation is its relatively surgical simplicity and the use of an external camera allowing a complex processing of images but its limitation comes from the relatively limited number of electrodes and the tedious rehabilitation work needed to understand and use the generated phosphenes by the patients.

The subretinal way using photodiodes is more physiologic and needs shorter rehabilitation training but is until now surgically challenging due to the wiring system needed to bring stimuli and power to the subretinal chip.

The next generation will probably use a totally wireless subretinal chip, stimulated by an infra-red laser sending information and power to the chip. The hope is to make a system surgically easy to implant and with better visual performances allowing an extension of indications to less severs visual impairments.