Not sure if I'm missing something. These sound like fluorescent dye particles? Don't such molecules emit light diffusely, i.e. not correlated to the direction

Not sure if I'm missing something. These sound like fluorescent dye particles? Don't such molecules emit light diffusely, i.e. not correlated to the direction of excitation? It also must be doing multi-photon fluorescence in order to bump up to higher (visible) frequencies. What is the point of putting it in a contact lens when it won't really echo the light field arriving at the lens? I also recall that infrared photography requires a significant adjustment of focus compared to visual light due to chromatic aberration. Would it even be possible for an IR-sensitive eye to accommodate this difference in focus? On the other hand, an efficient upconverting fluorescent dye could be embedded in an imaging screen with appropriate optics to make passive IR scope?