NEW YORK—Optical industry organizations and practitioners across the country are once again coming together to warn the public against the dangers of costume contact lenses worn without a prescription this Halloween season.

According to the American Optometric Association (AOA), contact lenses from any store or website that doesn’t require a prescription should not be bought. All contact lenses are classified as medical devices by the U.S. Food and Drug Administration (FDA) and require a prescription. The selling of lenses without prescription not only puts consumers’ eye health at risk but is also illegal.

"Don't buy contacts from any store or website that doesn't require an eye doctor's prescription," Glenda Secor, OD, chair of the AOA's Contact Lens and Cornea Section said. "In other words, if you can walk in off the street, or log on to a website and buy them without verification of your prescription, the lenses are not being sold legally."

The American Academy of Ophthalmology (AAO) is urging shoppers to stay away from over-the-counter lenses after a recent study found several varieties tested positive for chlorine and other harmful chemicals. Additionally, the study found that colorants printed or pressed onto some lenses created an uneven texture that could scratch the eye.

“You can’t be sure what you’re getting when you buy over-the-counter contact lenses, which can be very dangerous to your eyes,” said ophthalmologist Thomas Steinemann, MD, spokesperson for the American Academy of Ophthalmology. “If you want decorative contact lenses, get a prescription or steer clear of them. It’s not worth the risk to your vision.”

Improper use of cosmetic lenses or purchasing lenses without prescription can lead to many serious eye complications. These can include corneal scratches, conjunctivitis, corneal ulcers, bacterial infections, swelling, eye pain or even permanent loss of sight.

In their tips for making Halloween safe, Prevent Blindness suggests never buying non-prescription lenses and never sharing contacts with others. Additionally, the AAO is recommending individuals get examined and fitted for the right size contacts by a health professional and the AOA is urging people to use proper contact lens health practices to avoid eye injury.