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Study findings suggest coronavirus replicates in the eye

A new study into Italy’s first coronavirus patient has found she had traces of the virus in her eyes for several weeks, even after it had become undetectable in nasal swabs.

The research, published in Annals of Internal Medicine, is the latest piece of literature to establish a connection between COVID-19 and ocular fluids, suggesting the eye is not only a potential entry point for the virus, but also a source of contagion.

At present, researchers say there has been limited data on ocular samples from COVID-19 patients, however unprotected ocular exposure was thought to be responsible for infections in the Wuhan Fever Clinic, in China, in January. Further, SARS-CoV-2 (which causes COVID-19) RNA was detected in conjunctival secretions collected from the only patient with conjunctivitis out of 30 patients from a hospital in China.

In this latest study, researchers analysed samples from a 65-year-old woman who presented at the National Institute for Infectious Diseases in Rome. She was the first COVID-19 case in Italy after travelling from Wuhan.

The third day after she was admitted to hospital, health workers took an ocular swab due to persisting conjunctivitis. Viral RNA was detected and subsequent ocular samples collected with almost daily frequency returned positive results up to day 21, with declining virus concentration.

This table demonstrates the viral load in ocular and nasal swabs from the first detected case in Italy.

The researchers said the patient’s conjunctivitis improved significantly at day 15 and seemed to have been resolved at day 20.

Five days later it had become undetectable, however SARS-CoV-2 RNA was detected again in an ocular swab sample on day 27.

“[It was also] detected in ocular swabs days after it was undetectable in nasal swabs,” the researchers said.

“In addition, the cycle threshold values detected in the late ocular samples were lower than those observed in the nasal swabs, suggesting sustained replication in conjunctiva.”

The researchers said the findings demonstrated that ocular mucosa may be not only a site of virus entry but also a source of contagion.

They said it highlighted the importance of appropriate personal protective equipment use among ophthalmologists during clinical examination.

“Furthermore, we observed that ocular involvement of SARS-CoV-2 may occur early in the COVID-19 course, suggesting that measures to prevent transmission via this route must be implemented as early as possible,” the concluded.

“Future studies are needed to define the human ocular cell types capable of supporting viral replication and the mechanisms underlying ocular tropism of SARS-CoV-2.”