Coronavirus may not be capable of infecting humans through their eyes, study suggests

Author: “It’s still possible a subset of people may have corneas that support growth of the virus, but none of the corneas we studied supported growth of SARS-CoV-2.”

ST. LOUIS — A coronavirus barrier, which stops the deadly virus from entering our bodies, has been discovered in the eye, according to a new study. The eye’s clear outer layer — the cornea — appears to resist COVID-19, despite being an entry point for other viruses, researchers say.

Herpes and Zika can infect the cornea before spreading to other parts of the body, but SARS-CoV-2, the virus that causes COVID-19, cannot get a “foothold,” the scientists say. Understanding how the coronavirus enters the body will help determine what PPE is needed to stop the deadly virus from spreading.

“Our findings do not prove that all corneas are resistant,” says study lead author Assistant Professor Dr. Jonathan Miner at Washington University School of Medicine in a release. “But every donor cornea we tested was resistant to the novel coronavirus. It’s still possible a subset of people may have corneas that support growth of the virus, but none of the corneas we studied supported growth of SARS-CoV-2.”

The eye is a window that welcomes viruses — except COVID?

The researchers wanted to see if the eye might serve as an entry point for COVID-19. Previous research has shown Zika virus can be shed in tears.

Mouse and human corneas were studied after being exposed to three viruses: herpes simplex, Zika and SARS-CoV-2.

“Some COVID-19 patients get eye symptoms, such as conjunctivitis (pinkeye), but it’s not clear that the viral infection itself causes that,” explains co-author Professor Rajendra Apte. “It could be related to secondary inflammation. The cornea and conjunctiva are known to have receptors for the novel coronavirus, but in our studies, we found that the virus did not replicate in the cornea.”

Key substances in the cornea tissue that encourage or restrain viruses were identified by the researchers. Interferon lambda, one of the substances, stopped the herpes simplex and Zika viruses from growing in the cornea, the researchers found. But it had no effect on COVID-19, which could not get a foothold regardless of whether interferon lambda was present or not.

“Our data suggest that the novel coronavirus does not seem to be able to penetrate the cornea,” says Apte.

Whether the deadly virus can grow in other tissue around the cornea, such as the tear ducts and the conjunctiva, is yet to be determined.

“It’s important to respect what this virus is capable of and take appropriate precautions,” notes Miner. “We may learn that eye coverings are not necessary to protect against infection in the general community, but our studies really are just the beginning. We need larger clinical studies to help us better understand all the potential routes of SARS-CoV-2 transmission, including the eye.”

The findings are published in the journal Cell Reports.

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