To see if the treated mice could actually see in the IR range (700 nanometers to 1 millimeter), they checked the pupils of the injected mice and noted that the test animals' eyes constricted when shown 900 nm light, while the controls (not treated) mice did not.
Then, researchers gave the mice a choice of two boxes: one that was completely dark and one illuminated by near-infrared light. Control mice spent time in both boxes, but mice with nanoparticle treated retinas chose the dark box, suggesting that they could see the near-IR light and preferred the dark.
This research has tons of applications. All of which are fascinating. I plan to keep an eye on developments in mammalian night vision. Who knows? Maybe someday everyone will have excellent night vision and no one will stub a toe in the dark. Go science!
