Contact lenses convert IR into visible light without a power source; enable people to see IR and visible light simultaneously in the dark

https://www.eurekalert.org/news-releases/1084046

"wearer can perceive multiple IR wavelengths, enhanced when eyes closed... flickering IR could be used to transmit information in security, rescue, encryption, anti-counterfeiting... nanoparticles combined into standard soft contact lenses absorb IR/ convert to visible... differentiation between different IR spectra by color-coding different IR wavelengths enables more perception details within fIR spectrum, also helping color blind people to some extent... embedding in glasses instead of contact lenses improves resolution"