Researchers detected SARS-CoV-2 RNA in the corneal discs of 6 of 11 patients with coronavirus disease 2019 (COVID-19) in a case series of autopsies performed between March 20, 2020, and May 14, 2020. Their findings were published in JAMA Ophthalmology.
The researchers sought to discover more detailed knowledge on virus tropism in the corneal tissue to provide guidance on best practices for cornea transplants, which are “the most frequently transplanted tissue worldwide,” according to the study.
Prior to autopsy, a conjunctival smear was obtained from 11 deceased patients (mean age of 68.5 years) with COVID-19 in Germany. An aqueous humor (AH) sample was obtained through 1 clear cornea from each of the 7 patients who had sufficient liquid for processing.
They performed autopsies and screened the patients for the virus with a throat smear and reverse transcriptase–polymerase chain reaction (RT-PCR). The mean postmortem interval was 2.7 days.
In 6 of 11 corneal disc samples, the researchers detected SARS-CoV-2 RNA. In 4 of these 6, subgenomic RNA (sgRNA) was detected. Virus isolation failed in all corneal disc samples.
Patients with SARS-CoV-2 RNA detected in the corneal disc also had positive results for SARS-CoV-2 RNA in 4 of 6 conjunctival swab samples, 1 of 3 AH samples, 3 of 5 vitreous humor (VH) samples, and 4 of 5 blood samples. SARS-CoV-2 RNA was detected in 5 of 11 conjunctival swab samples, 3 of 7 AH samples, and 6 of 11 VH samples. Postmortem SARS-CoV-2 viremia was detected in 5 of 9 patients.
SARS-CoV-2 spike protein-positive cells could not be detected by immunohistochemistry regardless of PCR result for SARSCoV-2 PCR. Staining on leukocyte common antigen (LCA) showed some LCA-positive cells in corneal discs.
“The potential of SARS-CoV-2 infection via a corneal transplant is low, but further research is warranted to assess the rate of SARS-CoV-2 transmission,” the study shows. “The low RNA loads in corneal samples suggest a low risk of infection through a corneal transplant, even in a high-risk cohort of patients with viremia. Nevertheless, infection via a contaminated corneal graft cannot be fully excluded.”
Limitations of the study include risk of selection bias due to prioritization of patients with viremia and small sample size and lack of a homogenous cohort due to including patients both with and without viremia.
Disclosure: One study author declared affiliations with industry. Please see the original reference for a full list of authors’ disclosures.
Casagrande M, Fitzek A, Spitzer MS, et al. Presence of sars-cov-2 rna in the cornea of viremic patients with covid-19. JAMA Ophthalmol. Published online January 21, 2021. doi:10.1001/jamaophthalmol.2020.6339.