Federal health officials are warning people not to use decorative contact lenses as part of Halloween costumes. Decorative lenses sold without a prescription are illegal and can cause serious eye injury and even blindness, the Food and Drug Administration (news - web sites) said Thursday. The lenses, which come in various colors and designs, have been sold without prescription in beauty salons, flea markets, convenience stores and beach shops and online, the agency said. The lenses can lead to corneal ulcers, eye infection or swelling, allergic reactions and vision problems, the FDA (news - web sites) said, citing injury reports it has received.