I have no idea how these work, but one hack idea off the cuff:

You get the light for free. At least when your lids are open; that's how vision works. A cheap digital watch lasts ages on a tiny coin cell because the polarisation of the LCD, which passes or blocks polarised light, takes minimal energy. Stack up a passive polariser, and the active LCD-like layer, (and maybe a second passive layer?) and you can cast selective shadows on the retina.

This gives you monochrome "smart vision" in the same sense as a monochrome Casio wristwatch. No idea how to tackle issues of focus at such a short focal length, or achieving any sort of active display let alone colour.

Maybe the whole thing is a pipe dream crackpot idea.

Light intensity is inversely proportional to the square of the distance. A light that's only a few microns away from your cornea would look incredibly bright even with minimal power.