COVID-19 has been found in conjunctival swabs and tears from infected patients, according to a new study published in The Ocular Surface.
The discovery prompted a research team that included Shahzad Mian, MD, an ophthalmologist at the Kellogg Eye Center, to analyze the prevalence of COVID-19 in post-mortem human eye tissues.
The results: The virus can infiltrate corneal tissue, the transparent outer layer of the eye, which could be used for transplants in the US, raising concerns that the disease could be transmitted to a healthy recipient.
Of the 132 eye tissues from 33 donors destined for surgery in Michigan, Illinois, Ohio and New Jersey, 13% tested positive for COVID-19, which was determined by isolating ribonucleic acid (RNA), a DNA-like molecule, of the patients known to have the virus or showed symptoms without a positive nasopharyngeal smear.
Studies have shown that COVID-19 patients have much of the virus in the upper respiratory tract, so there is a strong possibility that the virus can contaminate the outer layers of the eye through respiratory droplets after coughing, sneezing. or the contact of the hands with the eyes, according to Mian.
There is no evidence to suggest that COVID-19 can be transmitted from a cornea transplant, but our data assures us that a screening process to determine who is positive for the virus and who is not is important to make sure we do everything. in case there is a potential risk of transmission. “
Shahzad Mian, MD, ophthalmologist, Kellogg Eye Center
The findings also demonstrate the critical importance of postmortem nasopharyngeal swab testing in detecting COVID-19 prior to transplantation. The study donors were divided into three groups:
This group was positive for COVID-19 after receiving a nasopharyngeal swab at the time of corneal recovery.
This group was made up primarily of donors since the beginning of the pandemic when testing was not widely available. Most of these donors tested negative for COVID-19.
This group had no signs or symptoms of COVID-19 and tested negative, but also spent a lot of time with someone who tested positive.
This is significant because 15% of the Group 2 corneal samples had COVID-19 RNA, despite having a negative nasopharyngeal smear test. In fact, this was even greater than the presence of Group 1 coronavirus-infected corneal tissue, which only had an 11% positivity rate despite donors having positive nasopharyngeal swab tests.
Neither tissue from the two Group 3 donors had the presence of COVID-19 RNA.
Decrease the presence of COVID-19 in the cornea
In addition to establishing a screening process, Mian set out to find out if there was a way to reduce the presence of COVID-19 in donor tissue, another strategy that could lower the risk of transmission.
“One goal of the initial study was to test the efficacy of povidone-iodine, a disinfectant, in inactivating COVID-19,” says Mian.
This was done by retrieving the donor’s right eyes without cleaning them with povidone iodine and following the double povidone iodine soak procedure recommended by the Eye Bank Association of America for the left eyes.
The procedure involves soaking the cornea in 5% povidone-iodine for five minutes, then rinsing with sterile saline. This is repeated after collecting a corneal tissue sample. All of the eyes that underwent this disinfection tested negative for COVID-19 RNA, compared to one of the swabs from the right eye that tested positive.
However, the team cannot conclude that povidone iodine is effective in reducing COVID-19 in corneal tissue because this procedure was only performed in 10 patients.
“A larger study is needed to confirm our findings, but we are excited about the possible implications of this research. These questions are important in keeping our patients healthy and safe,” says Mian.
It is not clear whether the presence of COVID-19 RNA is due to an infection of the ocular surface or to the transport of the virus from the upper respiratory tract through the tear ducts. It is also unclear whether COVID-19 can replicate in corneal cells and what changes occur in these cells when they become infected.
“The conclusion that I hope other clinicians will have as they read this study is that following elaborate donor screening procedures to mitigate the risk of pathogen transmission during transplantation, as well as screening donors postmortem for COVID-19 specifically, when there is no COVID-19 the nasal swab test is of vital importance as professionals in this field. “
Michigan Medicine – University of Michigan
Sawant, OB, et al. (2020) Prevalence of SARS-CoV-2 in human post-mortem ocular tissues. The ocular surface. doi.org/10.1016/j.jtos.2020.11.002.