Craig Melvin is living proof that sleeping in your contact lenses is a bad idea.
The TODAY anchor wore glasses on the air Thursday for the first time in his 15-year career because he developed a corneal ulcer in his left eye.
How'd it happen? He fell asleep with his contacts in.
"Don't let this happen to you!" Craig cautioned TODAY fans.
Dr. Annie Negrin, an ophthalmologist from Purchase, New York, joined the TODAY team to shed some light on how corneal ulcers occur, and how the approximately 45 million Americans who wear contact lenses can avoid getting one.
"It's a sore in the eye,'' Negrin said. "It's a break in the skin of your cornea. So if you wear the contact lenses for too long, and even in the best lenses, you have a relative lack of oxygen getting to the cornea and that gives those nasty bacteria a chance to get in there, bind to your cornea and kind of burrow their way through."
There are about 1.5 million corneal ulcers diagnosed annually among 85 million contact lens wearers worldwide, mainly due to people sleeping in their lenses overnight or not practicing good hygiene, according to Negrin.
If Craig had not gone to the eye doctor on Wednesday and continued to wear his contact lenses, it could have led to scarring.
"Once your cornea scars, it doesn't regenerate,'' Negrin said. "He's not going to see through that part of his scar. And even worse, if it really went on, it could go into your eye, and it could lead to blindness. It's actually a pretty serious complication."
Craig's corneal ulcer is minor compared to the six contact lens horror stories shared by the Centers for Disease Control earlier this month about the dangers of sleeping or swimming with them in. One man had to undergo a corneal transplant, while a British woman grew a cyst when a lens was stuck under her eyelid for 28 years.
Craig could be wearing his glasses for anywhere from a few days to a couple weeks as his eye recovers. He went crowd-sourcing on Instagram Wednesday to see which specs looked best.
"It really depends on the size of the ulcer when you presented it to the doctor, the location and how deep it was,'' Negrin said. "If you went relatively early, maybe about a week, but I've seen ulcers take up to three weeks."
Carson Daly, who also has issues with contact lenses at times, said he finds daily contact lenses to be the best choice.
"You should get the disposables,'' he told Craig. "You get a million of them and just throw them away."
Negrin advises her patients to use the daily contacts. She also stresses good hygiene, which means washing your hands before putting the lenses in your eyes.
"Even if you're falling asleep at your computer, you've got these long hours, you don't even need to put them in solution or to clean them, you just toss them and start a new pair,'' she said.
Savannah Guthrie, who also wears contacts and glasses, noted that she has tried the disposable kind and didn't like them. Both could always just go the route of Al Roker, who's always rocking stylish eyewear.
"Shouldn't you just wear glasses, forget about contacts?" he said.
Follow TODAY.com writer Scott Stump on Twitter.