COVID-19 News: Post-Mortem Study Shockingly Reveals Prevalence Of SARS-CoV-2 Coronavirus In Eye Ocular Tissues
: A Post-mortem study by ophthalmologist and researchers from the Center for Vision and Eye Banking Research, Eversight-Cleveland, Wayne State University-Detroit, Rush University-Chicago and the University of Michigan have shockingly found the prevalence of SARS-CoV-2 coronavirus in eye ocular tissues.
These findings were of a concern and could have varied implications.
The study findings showing that SARS-CoV-2 coronavirus had been found in conjunctival swabs and tears of infected patients were published in the peer reviewed journal: The Ocular Surface. https://www.sciencedirect.com/science/article/pii/S1542012420301683
The shocking discovery prompted a study team including Dr Shahzad Mian, M.D., an ophthalmologist at Kellogg Eye Center-University of Michigan, to analyze the prevalence of COVID-19 in human post-mortem ocular tissues.
The study team found that the SARS-CoV-2 coronavirus can infiltrate corneal tissues, the clear, outer layer of the eye, that could be used for transplantation in the U.S. and elsewhere raising concerns that the disease could be transmitted to a healthy recipient.
In the study of 132 ocular tissues from 33 donors intended for surgery in Michigan, Illinois, Ohio and New Jersey, 13% were positive for COVID-19, which was determined by isolating the ribonucleic acid (RNA), a molecule similar to DNA, of the patients that were known to have the virus or showed symptoms without a positive nasopharyngeal swab.
Past research have shown that COVID-19 patients hold much of the SARS-CoV-2 virus in the upper respiratory tract, so there's a strong possibility the virus could contaminate the outer layers of the eye via respiratory droplets after coughing, sneezing or hand-to-eye contact, according to Dr Mian.
Dr Mian told Thailand Medical News, “However to date, there is no evidence to suggest COVID-19 can be transmitted from a corneal transplant, but the study data assures healthcare professionals that a screening process to determine who's positive for the virus and who isn't is important to make sure they do everything in case there is a potential risk of transmission."
The study findings also demonstrate the critical importance of post-mortem nasopharyngeal swab testing for detecting COVID-19 before transplantation.
For the research, the 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 primarily made up of donors from early in the pandemic when testing wasn't widely available. The majority of these donors had a negative COVID-19 test.
This group didn't have signs or symptoms of COVID-19 and tested negative, but they also spent extended amounts of time with someone who tested positive.
The findings were significant because 15% of the corneal samples from Group B presented with COVID-19 RNA, despite having a negative nasopharyngeal
swab test. In fact, this was even higher than the presence of coronavirus-infected corneal tissue from Group A, which only had a positivity rate of 11% despite the donors having positive nasopharyngeal swab tests
Interestingly none of the tissues from Group C's two donors had a presence of COVID-19 RNA.
Besides establishing a proper screening process and protocol, Dr Mian set out to discover if there was a way to lower the presence of COVID-19 in the donor tissue ie another strategy that could diminish transmission risk.
Dr Mian said, "An initial study goal was to test the effectiveness of povidone-iodine, a disinfectant, in inactivating COVID-19."
The study was done by recovering donors' right eyes without cleaning with povidone-iodine and following the Eye Bank Association of America recommended double povidone-iodine soak procedure on the left eyes.
The disinfecting procedure involves soaking the cornea in 5% povidone-iodine for five minutes, then flushing with sterile saline fluid. This is repeated after a sample of corneal tissue is harvested.
All of the eyes that underwent this disinfecting tested negative for COVID-19 RNA, compared to one of the right eye swabs that tested positive.
The study team was unable to conclude that povidone-iodine is at all effective in reducing COVID-19 in corneal tissue because this procedure was only performed on 10 patients.
Dr Mian stressed, "A larger study is needed to confirm our findings, but we're excited about this research's potential implications. These questions are important in keeping our patients healthy and safe.”
Importantly it is still unclear whether the presence of COVID-19 RNA is due to ocular surface infection or due to transport of the virus from the upper respiratory tract via the tear ducts. It's also unclear whether COVID-19 can replicate in corneal cells and what changes occur in these cells when infected.
In the context of the route of administration, it has been proposed that the SARS-CoV-2 virus travels via direct airborne transmission since the entire ocular surface including the anterior cornea, tear film and conjunctiva communicates with air, similar to the nasal mucosa. Another proposed path of infiltration is the nasolacrimal route, facilitating the transport of viral particles from the respiratory tract to the ocular surface or vice versa. https://www.sciencedirect.com/science/article/pii/S1542012420300975
These potential routes of infiltration may justify reports suggesting that SARS-CoV-2 causes conjunctivitis in COVID-19 positive patients.
Incidences of conjunctivitis in these reports are mainly in the range of 0.8–6% but they can be as high as 32% and 66%. https://journals.lww.com/co-ophthalmology/Abstract/2020/09000/Eye_banking_in_the_coronavirus_disease_2019_era.14.aspx
Taken together, all these findings also suggest that ocular surface specific therapeutics could mitigate traffic of virus between ocular surface and upper respiratory tract. It has been postulated that ocular surface heparan sulphate could be serving as an entry-point for SARS-CoV-2. https://www.mdpi.com/2077-0383/9/6/1885
Therefore, anti-heparan sulphate inhibitors could be an attractive anti-viral agent since this approach has already been shown to be effective against corneal Herpes Simplex Virus-1 infection. https://iovs.arvojournals.org/article.aspx?articleID=2482875
The study team commented, "The takeaway is that we hope other physicians have when reading this research findings, following elaborate donor screening procedures to mitigate the risk of pathogen transmission during transplant, as well as testing post-mortem donors for COVID-19 specifically, when there is no COVID-19 nasal swab testing, is critically important as professionals in this field."
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