How do Casino combat marked cards with special contact lenses

Concerned poker player

Execution.

Do you have special reason to fear that your being taken advantage of at a casino? Or secret knowledge of a contact lens material that is unable to be made into a camera lens, that only players can obtain, but not security personnel?

casinos spend millions of dollars annually to ensure that play is fair. Any casino that didn't would lose it's customers.

Many casinos use automatic shufflers now that count the cards each shuffle and detect any anomalies. Pretty much any attempt at marking would result in immediate detection and the table being detained until it was determined whether it was malicious intent or accidental.