Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for COVID-19, can infect various human tissues, including the eye. A recent study examined the changes and cellular presence of SARS-CoV-2 in ocular tissues during autopsies.
Interestingly, despite evidence of SARS-CoV-2 infection in the eye, researchers observed a notable absence of inflammation, a contrast to typical viral eye infections. These findings are published in The American Journal of Pathology.
Although ophthalmic manifestations and tissue tropism of SARS-CoV-2 have been linked to COVID-19, the specifics of SARS-CoV-2 pathology and cellular presence in ocular tissues remain relatively uncharacterized.
Dr. Daniel S. Chertow, the lead investigator from the Emerging Pathogens Section, Critical Care Medicine Department, Clinical Center, and Laboratory of Virology at the National Institute of Allergy and Infectious Diseases, explains, "The eye is an immune-privileged site and so may serve as a location for viral infection and persistence. We therefore sought to determine if eye tissues become infected with SARS-CoV-2, and if they do, what damage might be associated with this infection."
A group of investigators conducted a post-mortem examination of the eyes of 25 COVID-19 patients. They employed in situ hybridization (ISH) to analyze sections of ocular tissue from four of these patients, aiming to pinpoint the cellular location of SARS-CoV-2 spike gene RNA.
The remaining 21 patients had their contralateral eyes subjected to histopathological examination. Notably, SARS-CoV-2 RNA was detected in various ocular components, including neuronal cells in the retina, ganglion cells, corneal epithelia, scleral fibroblasts, and oligodendrocytes of the optic nerve in all 21 patients.
Typical histopathological findings related to the infection encompassed cytoid bodies, vascular alterations, and retinal edema. Interestingly, while SARS-CoV-2 managed to infect a variety of ocular cell types, the infection was characterized by minimal to no associated inflammation.
“In conclusion, a range of common histopathologic alterations were identified within ocular tissue, and SARS-CoV-2 RNA was localized to multiple cell types. What was surprising was the absence of inflammation, contrasting with what we have seen in other viral infections of the eye such as herpesvirus, where infection is typically associated with significant inflammation and tissue damage. The study shows important new insights into SARS-CoV-2 ocular pathogenesis. Specifically, this is the first report to definitively localize SARS-CoV-2 to the retinal inner and outer nuclear cells, retinal ganglion cells, and ocular surface by ISH, validating previous studies that have exclusively used PCR-based methods,” said Dr. Chertow.
This study underscores the eye's vulnerability to SARS-CoV-2 infection and reinforces the necessity to assess potential short- or long-term ocular effects of COVID-19.
H. Nida Sen et al, Histopathology and SARS-CoV-2 Cellular Localization in Eye Tissues of COVID-19 Autopsies, The American Journal of Pathology (2023). DOI: 10.1016/j.ajpath.2023.02.016