At a close-up magic show, the magicians may choose the invisible ink contact lenses. It will not be revealed by the audience, cause their naked eyes cannot see the mark clearly.
In that case, maybe a banker works in casino has one chance to see this magic show, and he has briliant idea to import the marked cards infrared contact lesnes into the casino to work as a anti poker cheating device.
This way the dealer or the banker can use the poker cheat contact lenses to check if there is any luminous ink mark playing cards be used on the poker game. If checked the cheat cards out before the game, it can help the casino be cheated or other poker players lose money.