In a new study, researchers suggest the eye’s cornea can resist infection from the novel coronavirus.
Although the herpes simplex virus can infect the cornea and spread to other parts of the body in patients with compromised immune systems, and the Zika virus has been found in tears and corneal tissue, SARS-CoV-2, the virus that causes COVID-19, does not appear to replicate in the human cornea.
The researchers have yet to determine, however, whether other tissue in and around the cornea, such as the tear ducts and the conjunctiva, is vulnerable to the virus.
The research was conducted by a team at Washington University School of Medicine in St. Louis.
In the study, the team examined mouse and human corneas exposed to the herpes simplex, Zika, and SARS-CoV-2 viruses.
Prior research in human and mouse corneal tissue had demonstrated that the Zika virus could be shed in tears, and the researchers wanted to learn whether the cornea might serve as an entry point for SARS-CoV-2.
They tested that by exposing the eye tissue to the different viruses and observing whether they could grow in and replicate. They also identified key substances in corneal tissue that can promote or inhibit viral growth.
One inhibitor they identified is called interferon lambda. They found that interferon lambda prevented efficient growth of the Zika virus and herpes simplex virus in the cornea.
But with SARS-CoV-2, levels of the substance had no effect on whether the virus could replicate. It simply could not gain a foothold whether interferon lambda was present or not.
This suggests COVID-19 probably cannot be transmitted through a cornea transplant or similar procedures in the eye.
However, because of unknowns involving the tear ducts and the conjunctiva, it’s too soon to dismiss the importance of eye protection.
Researchers need larger clinical studies to help better understand all the potential routes of SARS-CoV-2 transmission, including the eye.
One author of the study is Jonathan J. Miner, MD, Ph.D.
The study is published in Cell Reports.
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