A new study has shown that the COVID-19 virus can breach the blood-retinal barrier (BRB) during systemic infection and damage the eye.
In the paper published in PLOS Pathogens, the researchers said that SARS-CoV-2 is known to cause several ocular manifestations in COVID-19 patients.
However, the role of eyes in viral transmission remains unknown. The presence of viral remnants in various ocular tissues and fluids from COVID-19 patients has led to an assumption that SARS-CoV-2 may be transmitted through the eyes.
The results from the study suggest that SARS-CoV-2 ocular exposure does not cause lung infection and moribund illness despite the extended presence of viral remnants in various ocular tissues.
In contrast, intranasal exposure not only resulted in SARS-CoV-2 spike protein presence in different ocular tissues but also induced a hyperinflammatory immune response in the retina.
The researchers also found that long-term exposure to COVID-19 impacted visual function of mice. They found the spike protein caused microaneurysms, retinal atrophy, retinal pigment epithelium mottling, and vein occlusion in the retina.
“Unexpectedly, the corneal epithelium was found to be resistant to SARS-CoV-2 infection, and ocular exposure of SARS-CoV-2 failed to cause lung pathology and moribund illness,” the study authors said.
“Cells lining the BRB showed induced expression of viral entry receptors and enhanced susceptibility towards SARS-CoV-2-induced cell death, which is further potentiated with comorbidities such as hyperglycemia.”
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