With Halloween costumes getting more and more elaborate, some people may go the extra mile and look for decorative contacts to change their eye color. But the Department of Homeland Security warns that fake contacts could be extremely dangerous.

“Make no mistake, contact lenses are medical devices that should be prescribed by trained professionals," said Peter Edge, a Homeland Security official. "Halloween is a fun and festive holiday, and nobody wants to see those celebrations end with a trip to the ER.”

Feds say not to buy any contacts that don't require a prescription. Non-prescribed contacts can cause blindness and corneal ulcers. This includes so-called "anime" lenses, which attempt to give the wearer wide, Japanese cartoon-style eyes.

DHS has launched what it is calling "Operation Double Vision" in an attempt to reign in sales of forbidden contacts, according to department spokesman Nestor Yglesias. So far more than 20,000 pairs have been seized this year.

"Contact lenses are like sponges that can absorb bacteria and cause an infection if not handled properly," said Jeffrey Hackleman, president of the Georgia Optomoetric Association. "A lifetime of good vision is so much more important than a cheap Halloween accessory.”