Don’t buy decorative contact lenses from beauty supply or novelty stores, the FDA warns. Also called colored, cosmetic, costume, theater, or fashion contact lenses, they are sold to change the appearance of eye color (not to correct vision problems).
Wearing any type of contact lenses without a prescription can damage your eyes, since they may not fit properly and buyers are not properly instructed on their use and care. Among the risks: redness and itching, corneal abrasions, decreased vision, infections, and possibly even blindness.
If you really want to enhance or change your eye color, consult a licensed eye care professional who can prescribe these special lenses.
Also see 6 Answers to Eye Color Questions.