The finding could point to a new eye-related symptom or side effect of COVID-19.

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We're all familiar with the most common symptoms of COVID-19: fever, a continuous cough, and a loss or change to the sense of smell or taste. But some potential symptoms and side effects uncovered by researchers have been more surprising, including this: A new study, published February 16 in the journal Radiology, found that some COVID-19 patients had developed nodules on their eyeballs.

What the new study said

The small study involving 129 French patients was a systematic review of brain MRI scans performed in patients with severe COVID-19, study lead author Dr. Augustin Lecler, from the University of Paris, tells Health. The eye nodules—a general term that commonly refers to a localized area of inflammation in or on the eye—were an unexpected finding, Dr. Lecler says.

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Credit: Adobe Stock / Design by Jo Imperio

"We did not think that we would discover any ophthalmological abnormalities, since ophthalmic involvement related to COVID-19 is very rare," Dr. Lecler explains. "Rapidly, we found these intriguing nodules of the posterior pole of the globe [the eyeball] which were visible only in the most severe patients: those placed in the prone position [meaning they were lying on their stomachs], intubated on high-flow supplemental oxygen, and sedated." Dr. Lecler says they were surprised to see the nodules, because they "had never been described before."

In the patients with nodules, the images produced by the brain scans reveal at least one nodule on the eye's macular region, which is integral to central vision. While the researchers don't know the exact cause of the nodules, it's possible that they could be linked to inflammation caused by the virus. Another theory is that the nodules could have been caused by the prone position itself; all of the affected patients in the study had been lying in the prone position when in an intensive care.

Did COVID cause the nodules?

It's not known. Nodules can attach to the eyeballs for many different reasons, including inflammation, infection, and cancer, Raphael Aharon, MD, a board-certified ophthalmologist in Forest Hills, New York, tells Health. He points out that in the French study, only three patients actually had eye exams, and they were considered normal.

"If you can't make a correlation between what is on an MRI and an ophthalmological exam, then it's really not helpful," says Dr. Aharon. "Moving forward, for patients who have MRI findings, a clinical correlation via an extensive ophthalmological exam would make it more relevant."

Dr. Aharon also notes that the nodules could be an incidental finding on the MRI without a clinical consequence. But if a clinical correlation could be found through further investigation, that would make it more important.

Dr. Lecler confirms that no abnormality was detected during a fundoscopy (a test that allows a health professional to see inside the fundus of the eye and other structures, routinely done as part of an eye examination) or using OCT, a high resolution technique to image the posterior pole of the globe. 

This means the researchers couldn't make a connection between the MRI and dedicated ophthalmological exams. "We are planning to perform radiological-pathological correlations in deceased patients, which will give us a greater understanding of the precise nature of the nodules," he says.

Other ways COVID might affect eye health

Scientists are still trying to figure out exactly how COVID-19 might affect eye health in general. In June 2020, a case study from the University of Alberta, published in the Canadian Journal of Ophthalmology, said conjunctivitis (also known as pink eye or red eye) can be a primary symptom of COVID-19, based on a 29-year-old woman with severe conjunctivitis and minimal respiratory symptoms who tested positive for COVID-19. "Red eye isn't a common manifestation of COVID-19, but it has been reported," Kathryn A. Colby, MD, chair of the department of ophthalmology at NYU Langone Health, previously told Health.

The American Academy of Ophthalmology has also said that the coronavirus can cause conjunctivitis. However, the Centers for Disease Control and Prevention (CDC) doesn't include this on its list of known COVID-19 symptoms.

Another recent study, published in BMJ Open Ophthalgmology, links eye issues to COVID-19. UK researchers suggested that sore and itchy eyes could be an early sign of infection, starting as early as two weeks before other symptoms appear. The study also mentioned photophobia (light sensitivity) as another possible sign of COVID-19 infection.

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDCWHO, and their local public health department as resources.

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