Looking ahead to Halloween, some partygoers may look to spice up their costumes with colored contacts, fashion lenses, and “circle” lenses that add decorative touches to the iris. These “costume contact lenses” (also known as cosmetic or decorative contact lenses) may seem fun and harmless, but they pose potentially serious dangers to the eyes of unsuspecting wearers. Just because decorative contacts can be purchased over-the-counter or on the Internet does not mean that they do not require the same level of care or consideration as a standard contact lens. The fact is that it is illegal to sell colored contact lenses without a prescription in this country, and there is no such thing as “one size fits all” contact lenses. Contacts that aren't properly prescribed and cared for can lead to allergic reactions, bacterial infections, corneal ulcers, and corneal scrapes. Some problems can end in blindness. Non-prescription costume contacts can cause cuts and open sores on the surface of the eyes that can lead to potentially blinding and painful bacterial infections. These can require corneal transplants and even cause permanent vision loss.