By looking at tissue samples from deceased donors, researchers found the virus was present in the eye itself—not just in the tears, as had previously been identified by scientists.
The study, which appears on the pre-print website medRxiv, has not been peer reviewed by a panel of experts, so findings should be interpreted with caution. However, the findings could have implications for eye tissue donation, which millions of people around the world require.
Researchers led by Onkar B. Sawant, from the Center for Vision and Eye Banking Research at Eversight, Ohio, analyzed 132 ocular tissues from 33 deceased donors after they were rejected for surgical use according to by the Eye Bank Association of America (EBAA) donor screening guidelines, eye bank medical director review or a positive COVID-19 test. They also investigated 20 eyes from an additional 10 donors who died of COVID-19.
From the 20 eyes recovered from the 10 donors, the researchers found evidence of SARS-CoV-2, the coronavirus that causes COVID-19, in various parts of the eye. This included the posterior and anterior corneal, and the vitreous—the gel like fluid that fills the eye. They also found SARS-CoV-2 spike and envelope proteins in the epithelial layer of the corneas.
The team says the study shows a “small but noteworthy prevalence of SARS-CoV-2 in ocular tissues from COVID-19 donors.” They say the results show how important sticking to donor screening guidelines are, as well as post-mortem testing and following disinfection protocols to make sure tissue harboring SARS-CoV-2 is not used for transplantation.
Sawant told Newsweek that previous reports have shown the virus can be present in the tears of COVID-19 sufferers and that it can cause conjunctivitis, which affects the membrane that covers the front surface of the eye and inner surface of the eyelids.
He said that having access to post-mortem ocular tissue meant they were able to carry out research on the presence of SARS-CoV-2 in the eye. The latest results are part of an ongoing study to do this.
“Our primary motivator is to ensure safe tissue for our surgeons and their patients,” he said. “Our secondary motivator is one that has driven the entire scientific community to conduct research around SARS-CoV-2: this is a novel virus and we are all eager to learn as much as we can about it to save and protect lives.”
Sawant said a systematic study of the virus in the human eye had not previously been carried out. “Determining the risk is critically important to ophthalmologists, eye tissue donation and cornea transplantation—and the millions of people globally in need of sight-restoring transplants,” he said.
Whether infected tissues used for transplants could transfer the virus is unknown. Sawant said more research would be needed to find that out, but said respiratory viruses generally are not known to transmit through human cell or tissue transplantation.
Current guidelines from the EBAA mean COVID-19 victims are disqualified from donating eye tissue for sight-restoring transplants. This has meant donor tissue availability has been more limited since the start of the pandemic, but the findings, Sawant says, have reinforced the importance of these guidelines.
Denize Atan, Consultant Senior Lecturer in Ophthalmology at the University of Bristol, U.K., who was not involved in the study, told Newsweek the findings confirm the virus can be found in ocular tissues. While it did not determine whether the tissues could transmit infection, “it does highlight the fact that the surface layers of the eye (conjunctiva, cornea, sclera) and tears are a possible route for transmission of the virus.”
“It is also possible that [the] virus could be transmitted from some of the tissues inside the eye.”
Sawant, who is Director of Research at Eversight, reiterated their research was in the primary stages, had not been peer reviewed and that the investigation was ongoing. However, he said that while the science around coronavirus is constantly evolving, the latest findings are in keeping with research by other teams.
“The science around SARS-CoV-2 is constantly evolving, and we continually monitor scientific findings by other researchers.”
Correction 10/16 10.55 a.m. ET: The number of tissue samples used and the group of donors involved in the research has been corrected.
