|Bionic implant in the eye|
The problem is that the interfaces are crude and it would seem that they work a bit like braille. For instance the brain interface uses the word "communicate" in quotes and describes the process thus:
Up to 100 implants or “channels,” each connected to tens of thousands of neurons, are able to record and encode information that a computer can recognize as representing specific neurological activity. However, this data is full of “noise,” and is frequently inaccurate.
It would seem that both it and the optical chip have a grid of active spots and leave the brain to interpret them. in the same way that the sense cells in the tips of the fingers can interpret the bumps of the braille and transfer the dot pattern to the brain to interpret them. This is a mechanism which clearly works whether or not you actually understand how the brain codes information internally.