Study Finds COVID-19 May Damage Vision

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In a study in mice, researchers found that the COVID-19 virus can infect the retina even when the virus doesn’t enter through the eyes.

The COVID-19 virus can breach the retinal barrier and potentially damage the eye, according to new research published in April 2024 in PLOS Pathogens.

Pawan Kumar Singh, Ph.D.

Pawan Kumar Singh, Ph.D.

“This finding is important as we increase our understanding of the long-term effects of SARS-CoV-2 infection,” Pawan Kumar Singh, Ph.D., an assistant professor of ophthalmology at the University of Missouri School of Medicine, said in a news release. “Earlier, researchers were primarily focused on the ocular surface exposure of the virus. However, our findings reveal that SARS-CoV-2 not only reaches the eye during systemic infection but induces a hyperinflammatory response in the retina and causes cell death in the blood-retinal barrier. The longer viral remnants remain in the eye, the risk of damage to the retina and visual function increases.”

Previous research had shown that COVID-19 was able to infect various ocular tissues and fluids, but the mechanism was uncertain and some believed that COVID-19 could be disseminated through the ocular surface.

Singh and his colleagues at University of Missouri School of Medicine wanted to determine look at COVID-19 transmission through the eye and through inhalation to determine the impact on the eye. They conducted a study with mice that were infected with COVID-19 through either inhalation or directly into the cells lining the blood-retinal barrier.

They found that COVID-19 can infect the retina even when the virus doesn’t enter through the surface of the eyes. Additionally, COVID-19 that was a result of nasal passage infection was able to infect the cells of the blood-retinal barrier.

COVID-19 “not only infects the various parts of the eye via systemic exposure but also induces a hyperinflammatory immune and antiviral response in the retina,” researchers wrote.

Long-term exposure to COVID-19 impact visual function of the mice. They found the spike protein caused microaneurysms, retinal atrophy, RPE mottling (spots of the retinal pigment), and vein occlusion in the retina (a blockage of the vein that drains from the retina).

But they also found that exposure of the retinal barrier to the COVID-19 virus did not cause a lung infection. “Although we did not observe the spreading of the virus to systemic organs via ocular surface exposure, further studies on viral spread through the nasolacrimal duct are warranted,” researchers wrote.

Singh noted in the news release that the goal now is to better understand the cellular and molecular mechanisms of how the COVID-19 virus breaches the blood-retinal barrier and better treat COVID-19 induced eye complications before a patient’s vision is compromised.

Immunocompromised patients or those with hypertension or diabetes may experience worse outcomes for COVID-19 associated ocular symptoms. “For those who have been diagnosed with COVID-19, we recommend you ask your ophthalmologist to check for signs of pathological changes to the retina,” Singh said. “Even those who were asymptomatic could suffer from damage in the eyes over time because of COVID-19 associated complications.”

This research was supported through fundings from the University of Missouri and the National Institutes of Health/National Eye Institute.

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