A US study found the SARS-CoV-2 (Covid-19) virus is not only capable of penetrating both the retinal pigment epithelium (RPE) and the retinal vascular endothelium (RvEC) but also triggered a “significant amount” of apoptotic cell death among those cells.
Using a murine model, researchers at the University of Missouri also found hyperglycaemic conditions were associated with increased Covid-19 infectivity in cells lining the blood-retinal barrier. This is consistent with hyperglycaemia being known to induce endothelial dysfunction, compromising the integrity of blood vessels, and the findings of many clinical studies reporting increased incidence of SARS-CoV-2 infectivity, disease severity and mortality associated with Covid-19 in diabetics, reported the research team in PLOS Pathogens.
“SARS-CoV-2 not only infects the various parts of the eye via systemic exposure but also induces a hyperinflammatory immune and antiviral response in the retina,” they wrote. Despite the presence of viral remnants in ocular tissues from Covid-19 patients leading to an assumption that the virus may be transmitted through the eyes, “the corneal epithelium was found to be resistant to SARS-CoV-2 infection and ocular exposure to SARS-CoV-2 failed to cause lung pathology and moribund illness.”
