If you’ve ever been tempted to keep your contacts in overnight, you must read this: A 39-year-old man in Cincinnati, Ohio, slept in his contact lenses only to wake up with an infection that will likely leave him partially blind in one eye

Local12/WCKR-TV in Cincinnati reports that Chad Groeschen first noticed some itchiness in his eyes last month, which he chalked up to allergies. But the following day, Groeschen woke up with excruciating pain in his left eye and foggy, “opaque” vision—and that’s when he really started to worry.

After visiting a specialist, he learned that his eye was severely infected with a bacteria called Pseudomonas aeruginosa, which is associated with the use of “extended wear” lenses like the ones Groeschen uses. These lenses are actually FDA-approved for overnight wear, but doctors say infection can and—and does—happen, and sometimes leads to an ulcer forming in the eye.

Groeschen told Buzzfeed that his doctors said, “(the) contact kind of acts like a petri dish,” trapping the bacteria and allowing it to flourish.

RELATED: 27 Mistakes Healthy People Make

Now he is being treated with antibiotics and healing slowly, but he will likely need a cornea transplant to fully regain his vision. “It’s probably going to, even at the best when he heals, leave a substantial scar,” Dr. William Faulkner, an ophthalmologist who treated Groeschen at the Cincinnati Eye Institute, explained to Local 12.

Dr. Michelle Akler, medical director of Akler Eye Center in Dearborn, Michigan, told Health that even lenses approved for continuous wear aren’t necessarily safe for it.

“There are contact lenses that are approved for overnight wear, and even though that is an approved use there are many studies that show that this is the main risk factor for these severe sight-threatening infections like the one this person developed,” she said.

In fact, the American Academy of Ophthalmology released a statement back in 2013 that warned that “overnight wear, regardless of contact lens type, increases the likelihood of corneal infection,” adding that studies have shown people who use extended wear lenses have chances of infection that are 10 to 15 times that of daily wear users.

RELATED: The Best Sunglasses for Healthy Eyes

“The organism that gentlemen had is known to cause severe corneal scarring within a couple of days,” Akler said, adding “but it’s not very common.” Still, she notes that this underscores the importance of proper care for your lenses.

“I think the daily contacts are the safest and the most convenient for all of us with our busy lives,” she said. “We may not have time to appropriately care for the other types.”

For those who are not using a fresh pair of contacts each day, Akler recommends taking them out every night, and only using a commercial sterile solution to clean and store lenses.
She also adds that regardless of the contacts you wear, you should always visit a doctor right away if you are experiencing any redness or discomfort in your eye.

Noted.

RELATED: 20 Quick and Easy Ways to Get Healthier Fast

This article originally appeared on Health.com.