Don't buy contact lenses at Walmart.
My uncle Pete, he got these brand new contact lenses and he wore them for a couple of weeks, he got them at Walmart. All of a sudden his eye starts to itch, and he's always itching it, scratching day in day out. He thinks it's these new contacts, but he never got them dirty. He notices a glint and took it to a forensics expert who put it under a microscope. Walmart had put a little metal tracking chip inside the lens.