In advance of the national "Twilight" convention, the FDA's medical device wing is warning fans of the dangers of non-prescription contact lenses. Devotees of the mega-blockbusting book and film series sometimes buy decorative lenses to look more like vampires or werewolves, and the agency wants to spread the word that non-FDA approved contacts can be hazardous, possibly leading to blindness. Instead of buying lenses from street vendors or Halloween stores, the FDA advises "Twilight" fans to go through eye doctors and approved online retailers. Release (PDF)