Two interesting articles on work to replace and upgrade human vision.  To begin, Gizmodo covers research to replace the retina with a micro-camera.  The mission being to replace lost vision with a chip that would record and stimulate the natural optical nerves with a chip. 

The second article, from medGadget, reports on an attempt to embed a visual feed into something as basic as a contact lens.  This would allow for a wide range of use from tourism to combat assistance to gaming, as the feed, if combined with GPS and directional awareness, could be overlayed on what the viewer can see in the moment. This could also have influence on education and psychology by adding/removing visual influences which might cause stress or distraction.

Naturally, once somone’s retina is replaced, it should be simple to include this type of visual overlay.