Blackjack infrared contact lenses
The IR contact lenses are for the nearsightedness or farsightedness. It is used for casino games to see through playing cards, some special processed playing cards.
Barcode marked cards with invisible ink is one kind of back marked cards. The marks on the back of poker cards can be read with this contact lens, while human naked eyes can not. You can see the marked cards value and suits of each playing cards when you play the blackjack with the IR contact lenses.
With the IR contact lenses in blackjack, you can get points add up nearer to 21 than the dealer's hand. How exciting it would be.