Infrared vision

Mice can see near infrared if you inject some upconversion nanoparticles (with an appropriate stickem) into their eyeballs. A particle absorbs an infrared photon, winds up in a metastable state that lasts long enough for it to absorb a second, upon which it emits a visible photon (and probably something invisible as well, but never mind that).

They ran some tests to see if the mice could distinguish green from infrared, distinguish shapes, etc--and they pretty much could. The video goes on to suggest great things from enhancing human vision--soldiers wouldn't need night vision goggles--but

• The human eye has some chromatic aberration already; the focus for infrared would be farther farther off than the red. But the infrared would appear green. Our focus centers on the green. I leave to your imagination how fuzzy things will get with 2 different focus lengths for green light.
• Try to imagine persuading soldiers to get shots in their eyes. Just try. Don't forget that they carry powerful weapons.
• Night vision is also about intensifying small amounts of light, not just infrared.

I don't believe I'll volunteer for human trials, if any.