Here’s what you’ll learn when you read this story:New soft contact lenses use upconversion nanoparticles to convert infrared light into visible light. Because visible light is blocked by eyelids but infrared light passes through, it is also possible to see in infrared with closed eyes. This is why a team of researchers at the University of Science and Technology of China (USTC) in Heifi upgraded to infrared contacts. Because infrared wavelengths pass through the eyelid more easily than visible light, subjects wearing upconversion contacts could see in infrared with eyes closed. When they closed their eyes, they experienced an increase in sensitivity to infrared light, but became almost 200 times less sensitive to visible light.