What does a retinal implant need from the eye, and what is left when the eye cannot help? · Grey Matter

A retinal implant replaces only the dead photoreceptors, so it needs living bipolar or ganglion cells and an intact optic nerve to carry its signal to the visual cortex.

What does a retinal implant need from the eye, and what is left when the eye cannot help?

A retinal implant replaces only the dead photoreceptors, so it needs living bipolar or ganglion cells and an intact optic nerve to carry its signal to the visual cortex. That is why it suits retinitis pigmentosa and macular degeneration and cannot help after glaucoma, optic nerve damage or the loss of the eye. For those cases the alternative is to skip the eye and stimulate the visual cortex directly: in 2021 a 96-electrode array in the occipital cortex of a woman blind for 16 years produced points of light that let her make out some letters.