SATURDAY, Oct. 27 (HealthDay News) -- Wearing nonprescription decorative contact lenses that make your eyes look like those of creatures such as vampires or werewolves is a bad idea and could damage your eyes, an expert warns.

Many people use over-the-counter decorative contact lenses at Halloween or at other times of the year, even though they are illegal and may cause serious eye infections and possibly permanent vision loss.

"There is no such thing as a 'one-size-fits-all' contact lens," Dr. Randall Fuerst, chairman of the American Optometric Association's contact lens and cornea section, said in an association news release. "Consumers who purchase lenses illegally, without a prescription or without consultation from an eye doctor, put themselves at risk for serious bacterial infections, allergic reactions or even significant damage to the eye's ability to function, with the potential for irreversible sight loss."

Even though they're illegal, decorative lenses are marketed and distributed to consumers through sources including the Internet, flea markets, convenience stores and beauty salons.

A 2012 American Optometric Association survey found that 18 percent of Americans wear noncorrective, decorative or colored contact lenses. Of those, 28 percent said they bought the lenses without a prescription and from a source other than an eye doctor.

"Decorative contact lenses carry the same risks as corrective contact lenses," Fuerst said. "Because of this, it's important for consumers to obtain a prescription and familiarize themselves with the information available from an eye doctor to reduce the risk of infection."

A proper medical eye and vision examination ensures that contact lenses are suitable for a person, that the lenses are properly fitted and that the patient knows how to care for their contact lenses.

More information

The U.S. Food and Drug Administration has more about decorative contact lenses.