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.
It’s still not clear exactly how often COVID causes conjunctivitis, but it appears to be more common in young people. One early study at Wuhan Children’s Hospital in China reported that 22 percent of kids who were hospitalized with COVID there had eye symptoms. Of those, 55 percent had eye discharge. Since then estimates of eye symptoms have ranged from less than 1 percent to more than 30 percent in children, Singh and his colleagues reported in a recent review study that incorporated data from around the world. According to the American Academy of Ophthalmology, the estimated prevalence in adults is 1 to 3 percent, a number based on research in China.
Why is Arcturus causing so many red eyes?
Although there is not yet an official analysis to quantify the rate of conjunctivitis caused by the latest variant, chatter among experts and early evidence from India suggests that pink eye is fairly common—especially in kids under age 12, says Shahzad Mian, an ophthalmologist at the University of Michigan. Pink eye doesn’t usually occur in isolation; kids also often have a fever, sore throat, cough or other COVID symptoms, too.
The reason why some variants cause more eye problems than others likely depends on mutations in the virus’s spike protein that make it bond more strongly to cells in the eye, experts say. Just like in the nose, lungs and upper airways, cells in the conjunctiva and other parts of the eye express ACE2 receptors, which are binding sites for SARS-CoV-2.
Arcturus isn’t the first variant that has shown an affinity for receptors in the eyes. Early in the pandemic, studies show, the Beta variant was more infectious to conjunctival cells, compared with the previous Alpha strain—leading to a higher concentration of the virus and more eye inflammation in infected individuals.
If a variant can more easily bind to a receptor, more virus particles can infect the cells, leading to a bigger immune response, Singh says. “The COVID-19 virus spike protein comes in [and] binds to this receptor, and then it triggers a chain of events, which leads to inflammation,” he says.
A COVID infection can begin in the eyes and spread systemically, or it can begin somewhere else, and the systemic changes can affect the eyes, he adds. “It can happen either way,” Singh says.
What should you do if you develop pink eye?
Don’t panic. Arcturus does not appear to be any more likely than other variants to lead to hospitalization, serious complications or death, Patel says. Viral conjunctivitis generally lasts up to about a week and typically goes away without intervention.
At home, you can look for clues that might help you deduce whether a virus is involved. Viral pink eye often comes on suddenly, causing red and watery eyes that are “tearing all over the place,” Steinemann says. With a bacterial infection, discharge tends to be goopy, thick and sticky, whereas allergies cause extreme itching of the eyes and eyelids. Some symptoms can overlap, regardless of the cause.
If you notice red eyes along with a fever (another common Arcturus symptom) or other COVID-like symptoms, it wouldn’t hurt to take a COVID test. “In this day and age of COVID, if you have a viral infection of the conjunctiva,” Patel says, “it is not unreasonable to suggest you have a COVID test.”
More serious warning signs include pain and severe light sensitivity, which can suggest damage to the eye that should be checked out by a doctor to assess potential impacts on vision, Singh says. Thick yellow discharge indicates a bacterial infection that might require antibiotics. Blurry vision is another warning sign of corneal inflammation that might benefit from steroid drops.
If symptoms don’t get better, or if they worsen after a few days, Steinemann adds, it’s time to consult a doctor. Under a magnifying scope, an ophthalmologist can see enlarged glands, called follicles, that are unique to viral infections, as well as signs that indicate other causes of pink eye.
If you have pink eye from COVID, is there anything you can do to feel better?
Artificial tears, available at drugstores, can soothe discomfort, experts say. Cold compresses can also help. Try not to rub your eyes—both to avoid causing damage or secondary infections and to prevent transmission to other people.
If you have COVID and red eyes, the virus is sure to be in your tears, Patel says. So make sure to wash your hands, use separate towels from other people and avoid physical contact until the infection is gone.
ABOUT THE AUTHOR(S)
Emily Sohn is a freelance journalist covering health, science and the environment in Minneapolis.
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