UV lamps that kill viruses burn people’s eyes, doctors warn

Ultraviolet lamps designed to kill viruses and bacteria appear to cause unpleasant eye damage in some people. In a new article this month, doctors report several cases in which people have developed inflamed corneas as a result of exposure to UV rays from “germicidal lamps” put in place during the covid-19 pandemic. Some patients were not even aware that the lamps had been installed.

UV lighting has attracted a lot of attention lately, as radiation can degrade the stability of many germs. Specialized lamps have been used in the past to control outbreaks of other potentially airborne diseases, including tuberculosis. Now a lot companies is hospitals use UV light to disinfect parts and equipment.

The problem is that UV rays can harm humans too, as anyone who has ever had a sunburn knows. Exposure to UV rays can damage both our skin and our corneas, the transparent and protective outer layer of our eye. When this happens, it causes painful inflammation called photokeratitis.

In this new article, published in the journal Ocular Immunology and Inflammation, the authors describe seven cases in which people developed photokeratitis several hours after exposure to UV lamps. All cases were seen by doctors from the Bascom Palmer Eye Institute at the University of Miami Miller School of Medicine.

In addition to irritation and redness, some patients have experienced mild symptoms such as feeling like something stuck in their eye. Others had severe, painful burns and sensitivity to light. In three cases the lamps had been installed at home, while three of the patients had been exposed to work. In all of these cases, patients reported having been in direct contact with light without eye protection (a seventh case involved a person exposed to UV light in a dental office).

Fortunately, people’s symptoms were short-lived after treatment – usually a combination of lubricating eye drops, antibiotics, and steroids – and most resolved completely within two to three days. But these injuries aren’t the first of their kind to be seen during the pandemic. In early April, the authors, Hong Kong doctors, noted reported three similar cases in one family.

It is unclear whether UV lighting was really that useful during this pandemic. Sufficient UV radiation should be able to kill persistent coronavirus in the air or on surfaces and objects, such as protective masks used by healthcare professionals. But the exact type of UV radiation that is most effective in killing viruses (UV-C) is also very dangerous to humans, limiting the usefulness of this disinfection strategy in the real world. The World Health Organization now explicitly warns people not to disinfect using UV lamps for the same reason.

“Installing UV-C air disinfection in medical facilities requires well-trained technicians to avoid direct exposure of occupants,” the doctors wrote. “The authors advise all people to avoid direct exposure to UV-C germicidal lamps and to carefully follow the manufacturer’s recommendations.”

While this current study does not intend to weigh on the effectiveness of UV lamps for preventing covid-19, it reinforces why people should be careful with them at all times.