If you have ever played poker, then you might be well aware that this is a card game. Just like any other game, there is some scope of cheating in this game to which is possible using contact lenses marked cards. These cards have been tampered for cheating in poker game or other card games. They have an alteration in the back for players to identify the value and suit of the card using poker scanner system. It is widely used in illusions and magic tricks too. Some casinos also make use of these cards.
Overview of marked cards:
These cards look similar to standard deck of cards but are altered in a way so that the value of it can be read from the back side. It can be with the use of subtle markings or other ways. It serves a purpose to help magicians with their tricks. But these are also used for cheating in card games especially poker. A dishonest dealer or a tricky player might use this at the table to make a win. Sometimes the player might use a few marked cards combined with normal cards to avoid suspicion. But many a times even the whole deck is marked.
It is illegal to use marked cards for gambling in almost all countries and casinos. Some casinos use scanners to test the cards before a game to avoid any legal complications and give a fair chance of winning to all its players. It should be used only for entertainment purposes.