The presence of SARS-CoV-2 RNA, spike and envelope proteins in the corneas of COVID-19 donors has been reported, but the presence of viral RNA and antigens hasn’t equated to infection. In this study, presented yesterday at ARVO’s virtual conference, researchers examined the replication ability of SARS-CoV-2 in cornea tissue of human eyes from affected patients and to understand the innate immune response.

Eyes from healthy and COVID-19 donors were assessed in a variety of lab tests, including infecting primary human corneal epithelial cells from normal and diabetic donor corneas with SARS-CoV-2. Bioinformatics analysis was performed to determine differential gene expression, and polymerase chain reaction was used to assess the expression of innate inflammatory and antiviral genes and to confirm RNA sequencing data in corneal tissue and cells.

RNA analysis showed the presence of both positive and negative strands of SARS-CoV-2 viral RNA in the epithelium of COVID-19 donor corneas. This coincided with infiltration of CD45+ cells in the stroma and induced expression of inflammatory and antiviral genes. RNA analysis revealed significant upregulation of genes involved in the viral response, inflammation and injury along with induction of factors involved in modulation of the immune response.

The study confirms the presence of replicating SARS-CoV-2 viral RNA and antigen in the cornea of COVID-19 affected donors resulting in the production of inflammatory mediators and recruitment of CD45+ immune cells to the cornea.

Additionally, epithelial cells from diabetic patients had increased SARS-CoV-2 replication and immune response, suggesting that diabetes is a potential risk for ocular transmission of COVID-19.

“We could detect replicating virus in the tissues with an antiviral response,” the authors explained in the abstract of their study found on the ARVO website (www.arvo.org). “Interestingly, the cornea tissue from diabetic patients had higher permissivity to viral infection and antiviral immune response—signs of productive infection. Therefore, our finding indicates that SARS CoV-2 can infect and replicate in cornea tissue and diabetes condition can increase the susceptibility and severity of COVID-19.”