The human eye is 'susceptible' to coronavirus infection, new study warns

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Researchers widely believe that COVID-19, the disease caused by the coronavirus pandemic, is transmitted person-to-person, largely via respiratory droplets from coughs, sneezes and talking. A new study suggests it can also be transmitted through the eyes from the ACE-2 protein.

The study, which has not been peer-reviewed and is posted on the bioxriv repository, notes that oculuar cells, including conjunctiva, "are susceptible to infection by SARS-CoV-2."

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"...[T]hese results indicate that ocular surface cells including conjunctiva are susceptible to infection by SARS-CoV-2, and could therefore serve as a portal of entry as well as a reservoir for person-to-person transmission of this virus," the researchers from Johns Hopkins University and Yat-Sen University in China wrote in the study. "This highlights the importance of safety practices including face masks and ocular contact precautions in preventing the spread of COVID-19 disease."

The researchers looked at port-mortem eyes of people who did not die from COVID-19 and found the ACE-2 protein and TMPRSS2, "a cell surface-associated protease that facilitates viral entry following binding of the viral spike protein to ACE2," were present.

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" ... [T]he presence of ACE2 and TMPRSS2 in conjunctival and corneal epithelial cells supports the ocular surface as a secondary site of infection following respiratory tract, or possibly even as the initial portal of entry to an individual," the researchers added. "Infection of ocular surface cells could lead to the eye as being an important carrier, with ocular virus shedding constituting a significant mechanism for infection of other individuals."

They continued: "Our study therefore highlights the importance of safety practices in the general community to prevent infection and spread (hygiene, face masks) and need for extra caution among ophthalmologists."

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The findings come just days after another study found that COVID-19 is nearly 100 times more effective at infecting the human conjunctiva. Conjunctiva is the membrane that covers the eyeball and inner surface of the eyelids.

Shortly after it was declared a pandemic, the Centers for Disease Control and Prevention issued guidance to not touch your face to reduce the spread of the virus.

As of Monday morning, more than 4.1 million coronavirus cases have been diagnosed worldwide, more than 1.33 million of which are in the U.S., the most impacted country on the planet.