Andrew Carthew, a 59-year-old paramedic in Britain, woke up one day in June 2015 with a "weepy eye," the Bristol Post reports. Six weeks later, he lost sight in the eye; less than a year after that, he lost the eye completely. Now he's warning others about a little-known yet very serious danger of contact lenses. According to CBS News, Carthew, who says he always took proper care with his contact lenses, originally thought he had a common eye infection. Then came the "absolutely shocking" pain and sensitivity to light. It was like having a toothache on an entire side of his face, Metro reports. He spent weeks just lying in the dark, only leaving his house for hospital visits. He had to retire after more than 30 years as a paramedic.
It turns out Carthew had Acanthamoeba keratitis, a rare infection caused by an amoeba. While the amoeba is found in lakes, soil, and more, 85% of infections happen with people wearing contact lenses that are contaminated—typically because they were worn while bathing or rinsed with tap water. In the US, Acanthamoeba keratitis usually infects just one or two contact lens wearers out of every million, but NBC News reports there was an outbreak of it in 35 states in 2007. As for Carthew, antibiotics and even a corneal transplant were ineffective. Doctors had to remove his eye before the infection reached the optic nerve, which could have been fatal. He says he wants people to start paying attention to contact lens care to make sure the same doesn't happen to them. The CDC estimates 90% of people with hard contact lenses sometimes rinse them with tap water. (Not to mention all the other gross things we do with our contact lenses.)