Seeing both worlds at once

Either we're going to accept hand held screens debilitating our conversations, eye contact, and awareness OR some kind of implant OR liquid contact lenses [eCons]. Let me explain. We're all familiar with liquid crystal displays which are incredibly energy efficient. 

They change opacity to control light throughput, so how about materials that can vary refractive index? These could form eCons to work with heads-up imaging on traditional glasses [eGlasses], and switch rapidly between normal sight and virtual displays. Add blinking for control, and we're free to roam without bumping into things.

And what's more, we would avoid implants which present real danger if hacked. In contrast, eCons and eGlasses can easily be removed.