Groeschen, a 39-year-old man, woke up one morning with eye irritation that quickly worsened over the next few days.

Concerned, he sought help at the Cincinnati Eye Institute, where doctors delivered troubling news—he had contracted a serious bacterial infection caused by Pseudomonas. The source? Sleeping with his contact lenses in.Doctors explained that the bacteria can thrive under contact lenses, where it “incubates” overnight. The infection had begun to erode his cornea, causing vision loss. “It’s like trying to see through frosted glass,” his doctors said. Scar tissue from the infection would continue to affect his vision even after the infection cleared. His only option for regaining sight was a cornea transplant—a major procedure with a year-long recovery.

As the owner of a design restoration company, Groeschen was forced to step away from work. He noted that the contact lens packaging claimed overnight use was safe, but medical experts disagree. The American Academy of Ophthalmology warned in 2013 that sleeping in any type of contact lens significantly increases the risk of corneal infections.

Dr. William Faulkner, Groeschen’s physician, urges users to avoid overnight wear and follow proper hygiene, including replacing lens cases regularly and fully emptying old solution before refilling.