By Stephanie Stahl

PHILADELPHIA (CBS) — Changing the appearance of your eyes may seem like a cool idea for Halloween, but beware, doctors warn using decorative contact lenses can be downright scary.

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The CDC is tweeting warnings about decorative contact lenses for Halloween.

“If the contact lens isn’t fitted for your eye, then it may move around like it shouldn’t on the eye and that can put you at a higher risk of developing a scratch on your eye, which could lead to an infection,” Allison Babiuch, an ophthalmologist at the Cleveland Clinic, said.

Eye infections from decorative lenses can cause scar tissue and blood vessels to grow in the cornea, which can interfere with vision.

Experts say to be safe, contacts have to be fitted by a doctor who can take precise measurements and prescribe a lens that fits the size and curvature of the surface of your eye.

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The decorative contact lenses are illegal to sell without a prescription because they are medical devices regulated by the FDA.

There is no such thing as one size fits all, which is why doctors say contact lenses should not be bought anywhere that doesn’t require a prescription.

“If your eyes are uncomfortable when you put them in, take them out,” Dr. Babiuch suggested. “If your eyes are still red, watery, irritated, visions down after you take them out, you need to get evaluated.”

The CDC warns people not to get tricked into wearing decorative lenses that could be anything but a treat for your eyes.

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The Pennsylvania Department of Health has also put out a special warning about cosmetic lenses and advised retailers that by selling them, they are breaking the law.

Stephanie Stahl