Tissue in human eye resistant to Covid-19
Date: 06 November 2020 Tags: MiscellaneousIssue
Researchers have found that the cornea, which covers the iris and pupil – appears to be resistant to coronavirus infection in experiment.
Background
The novel coronavirus, SARS-CoV-2, mainly spreads through droplet transmission when a person coughs, talks or sneezes. But there were doubts regarding transmission through eyes.
Details
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SARS-CoV-2 RNA was found in the tears and conjunctival sac of some patients. Pink eye or mild conjunctivitis has also been seen in some patients with COVID-19.
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Experts indicate that the presence of RNA does not mean that the virus was actively replicating inside the conjunctiva; it may have just been the person shedding the virus from the conjunctiva.
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In experiments using corneal tissue from 25 human donors and also mice corneas, the researchers exposed the eye tissue to three separate viruses: SARS-CoV-2, Zika virus, and herpes simplex virus 1.
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In the human cornea explants, the experiment showed that herpes and Zika virus were able to replicate in the tissue but tests showed no sign of SARS-CoV-2 replication.
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As for how the human cornea and conjunctiva might be capable of resisting SARS-CoV-2, the team isn't entirely sure.
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A potential molecular inhibitor of viruses in the eye – called interferon lambda – was able to limit virus growth in the human cornea for HSV-1 and Zika virus, but blocking the protein didn't seem to boost SARS-CoV-2's ability to replicate.
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Health professionals should use protective eyewear until there is enough proof to indicate that the virus cannot enter the body through eyes.