Doctors warn about eye damage from UV lights to kill the coronavirus

People trying to kill the coronavirus with ultraviolet C germicidal lamps may risk painful eye injuries if they aren't careful, a recent study finds.

Florida researchers report at least seven cases of patients with UVC damage to the cornea, the eye's outer layer, that left them with burning sensations and sensitivity to light after they used the lamps, according to a report published in Ocular Immunology and Inflammation.

"The clear part of the surface of the eye happens to be very susceptible to the wavelength of the light from these lamps," said Dr. Jesse Sengillo, an ophthalmologist at the Bascom Palmer Eye Institute of the University of Miami Health System.

The eye damage is "like a sunburn to the cornea," Sengillo said. "It's quite painful, and it takes a couple of days to heal. People often have trouble opening their eyes because they are sensitive to light and their eyes are red and itchy. One patient said, 'My eyes are on fire.'"

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The burning sensation doesn't occur immediately, so some of the patients didn't realize they had damaged their eyes using UVC lamps hours earlier.

People who want to use the lamps should turn them on and then leave the room until it's time to turn them off, Sengillo said.

Sengillo suggests that anyone who has eye pain after having used the germicidal lamps see a doctor for ointments to ease the burning sensation and to get antibiotics, because such injuries are susceptible to infection.

Patients have continued to trickle into the Eye Institute, Sengillo said. "We have noticed that they seem to come in waves," he said. "We noticed, as Covid-19 infections have increased in Miami, cases of cornea damage are starting to pick up again."

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Beyond Miami, it's unclear how common UVC lamp eye damage is, but the reports didn't surprise Dr. Deepinder Dhaliwal, an ophthalmologist in Pittsburgh.

"We're all trying now to increase safety for the public, and these UVC devices can be very helpful antimicrobials," said Dhaliwal, a professor of ophthalmology at the University of Pittsburgh School of Medicine. The light they emit "looks relatively harmless, and if people aren't aware they shouldn't be looking directly into the light, they may not realize that it's harmful."

The Food and Drug Administration suggests that UVC radiation might inactivate SARS-CoV-2, the virus that causes Covid-19, but it warns about reports of skin and eye burns caused by improper installation of UVC lamps in rooms.

"People understand that when they go out in the sun, they can get sunburned," Dhaliwal said. "What they may not realize is that, even though this is UVC, it can also cause damage. The eye is vulnerable, and if you're going to use this kind of device, you should wear eye protection."

It's also possible that people might be somewhere that has a UVC lamp and not realize that it could hurt their eyes, Dhaliwal said. "If you enter a room and see a funny-looking light, don't look directly at it, and use eye protection."

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Linda Carroll is a regular health contributor to NBC News. She is coauthor of "The Concussion Crisis: Anatomy of a Silent Epidemic" and "Out of the Clouds: The Unlikely Horseman and the Unwanted Colt Who Conquered the Sport of Kings."