Contact lenses have never been so popular. More than 30 million people worldwide use the little convex plastic discs to improve their vision. But the rules around wearing them are often ignored by users. They’re not just snippets of advice that the optician dishes out. The rules are important – don’t follow them and you can find yourself in serious trouble. Just ask Chad Groeschen.

You should wash your hands before putting lenses in your eyes or taking them out. You need to clean them thoroughly with special solution. You shouldn’t shower while wearing them. And most of all? You shouldn’t go to sleep in them. Chad did. And just days later… He was blind.

The worst thing? Cincinnati-based Groescher was wearing ‘extended wear lenses’. The ones you can actually sleep in… He slept in them, woke up with a pain in his eye and had cloudy vision. The pain got worse. Friends urged him to go to the hospital. He was diagnosed with a pseudomonas bacteria infection. Soon after, though? He was blind in one eye.

This is a truly shocking story. Here’s what happened:

Think that’s crazy? Bionic contact lenses are even weirder…