By Emily Sohn on May 12, 2023 in The Scientific American. Thanks to Ed M.
A new variant of the virus that causes COVID is drawing international attention, not just for its rapid spread but for its tendency to cause one unexpected symptom: conjunctivitis, or “pink eye.”
The strain, known officially as XBB.1.16 and colloquially as Arcturus, is a subvariant of Omicron. It was first detected in India, where it has been spreading quickly, but it has been identified in dozens of countries and now makes up more than 12.5 percent of cases in the U.S., according to the Centers for Disease Control and Prevention. The World Health Organization has categorized Arcturus as a “variant of interest,” which means it has genetic changes that could affect its behavior, along with an advantage over other variants in circulation.
Everywhere it goes, Arcturus has generated reports of red, irritated eyes, especially in children. While bloodshot eyes can look alarming, experts say, viral pink eye isn’t usually anything to worry about on its own, and Arcturus is not showing signs of being more dangerous than previous variants. Still, knowing that pink eye might result from a COVID infection can help people detect it sooner and prevent further transmission.
Scientific American asked experts about why Arcturus appears to be targeting the eyes and when you should consult a medical provider.
WHAT IS PINK EYE, AND WHAT CAUSES IT?
Pink eye, known to doctors as conjunctivitis, describes inflammation of the conjunctiva—a thin, transparent mucous membrane that covers the white part of the eyeball. This inflammation causes blood vessels to become engorged, which is what makes eyes looks red or pink, says Thomas Steinemann, a clinical spokesperson for the American Academy of Ophthalmology.
Other symptoms of conjunctivitis can include watery eyes and a sensitivity to brightness as a result of an inflamed cornea, which splits light like frosted glass, says Bhupendra Patel, a plastic surgeon and specialist in eye disorders at the University of Utah’s John A. Moran Eye Center.
An estimated six million people in the U.S. see a health care provider each year for conjunctivitis, often because of viral infections, Patel and a colleague wrote in a review paper. Adenovirus is by far the most common cause of viral conjunctivitis and is responsible for 90 percent of such infections. Influenza, herpesviruses and other viruses can also cause pink eye. In addition to viruses, bacterial infections, chemical exposures, allergies, compromised contact lenses and physical trauma can trigger the condition.
WHY DOES COVID SOMETIMES CAUSE PINK EYE?
Experts have known since the pandemic’s beginning that COVID can cause eye symptoms such as pain, itching, burning and the telltale pink hue of conjunctivitis. Like other coronaviruses, including the SARS virus that caused an outbreak in 2002–2003, the COVID-causing virus SARS-CoV-2 has been isolated in tears. And higher concentrations of the virus in tears are linked to more severe eye symptoms, says Rohan Singh, an ocular immunology fellow at Massachusetts Eye and Ear, a Harvard Medical School–affiliated teaching hospital.
In fact, one of the first people to flag the existence of SARS-CoV-2 was Li Wenliang, a Chinese ophthalmologist who experts suspect caught the virus from an asymptomatic glaucoma patient. He eventually died from the illness.