SARS-CoV-2: RNA Genomics in Ocular Specimens
British Journal of Ophthalmology
Published online April 9, 2021
Casagrande et al. examined retinal and optic nerve biopsy specimens of deceased patients who had COVID-19. They found SARS-CoV-2 RNA in half of the retinal specimens and in most of the optic nerve specimens.
This study was performed in Germany and included 14 eyes of 14 deceased patients in whom COVID-19 had been confirmed. The researchers’ objectives were to understand infectivity via virus isolation and to detect and quantify SARS-CoV-2 RNA by real-time reverse transcriptase polymerase chain reaction. They obtained postmortem throat swabs and biopsy specimens of the retina, vitreous humor, and optic nerve, which underwent further exploration by virus cultivation/isolation, molecular analysis, and immunohistochemistry.
Thirteen of the 14 patients died of COVID; the other died of unrelated hemorrhagic shock. No documentation of COVID-related ocular symptoms was found in the patients’ medical records. SARS-CoV-2 RNA was observed in seven (50%) of 14 retinal specimens, 10 (77%) of 13 optic nerve specimens, and eight (57%) of 14 vitreous humor samples. SARS-CoV-2 viremia was found in six (55%) of 11 samples. Virus isolation failed in all vitreous humor, retina, and optic nerve specimens. Moreover, immunohistochemistry findings were negative for the SARS-CoV-2 spike protein. Subgenomic RNA was detected in 40% of retinal and 60% of optic nerve samples.
Although the presence of subgenomic RNA could denote SARS-CoV-2 invasion of neuronal tissue, said the authors, they believe this would be unlikely in the absence of virus isolation or spike protein detection. Hence, subgenomic RNA itself does not definitively denote active replication. The authors recommend larger studies of the ophthalmic features and effects of SARS-CoV-2 infection.
The original article can be found here.