Black cape? Check. Plastic fangs? Check. Scary make-up? Check. Contact lenses to make your eyes look blood red? Unless they've been prescribed and fitted by an eye care professional, leave your novelty lenses at home this Halloween. Casey Eye Institute physicians caution that you could experience your own horror story, namely the risk of permanent vision loss from a painful eye infection or serious injury.

The U.S. Food and Drug Administration (FDA) oversees the safety and effectiveness of contact lenses and considers them a medical device. Decorative lenses, often sold on the Internet and in beauty salons and novelty shops, are illegal if purchased or sold without a valid prescription from an eye doctor. 

"Costume contact lenses tend to be made from older materials, are thicker and can have 'surface' paint or tint that affects the comfort of the lens," explains Derek Louie, M.Sc., O.D., assistant professor of ophthalmology, who specializes in medical contact lenses at Case Eye Institute. "The lenses generally aren't designed to be worn regularly," he says.

Several factors are involved that cause eye problems from non-prescription lenses, such as poor lens fit. Not only are the lenses not manufactured according to FDA standards, but many times people are not trained to use or wear them properly.

While novelty lenses may top off your look for Halloween, the dangers outweigh the benefits and can happen quickly. Complications may include chronic eye irritation, viral or bacterial infections, or abrasions and ulcers of the cornea which can damage eye sight.

Dr. Louie points out that you should only purchase contact lenses for Halloween through your eye doctor. This ensures you are receiving exactly what has been prescribed and you know where to go if problems surface, says Dr. Louie.