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Screening vital to eliminating COVID transmission risk through donor cornea

Researchers have analysed the prevalence of COVID-19 in human post-mortem ocular tissues, highlighting the importance of the donor screening process.

Their results demonstrated that the virus could infiltrate corneal tissue that may be used for transplantation, raising concerns that the disease could be transmitted to a healthy recipient.

The study’s 33 donors intended for surgery in Michigan, Illinois, Ohio and New Jersey were divided into three groups.

The first group was positive for COVID-19 after receiving a nasopharyngeal swab at the time of corneal recovery. The second 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.

The third group – comprising two donors – 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.

Of the 132 ocular tissues from the 33 donors, 13% tested positive for COVID-19.

This was determined by isolating the ribonucleic acid molecule of the patients that were known to have the virus or showed symptoms without a positive nasopharyngeal swab.

Significantly, 15% of the corneal samples from the second group presented with traces of COVID-19, despite having a negative nasopharyngeal swab test. This was higher than the presence of coronavirus-infected corneal tissue from the first group, which only had a positivity rate of 11% despite the donors having positive nasopharyngeal swab tests, according to published results.

Dr Shahzad Mian, an ophthalmologist at Kellogg Eye Center in Michigan who was involved in the study, said that while there’s no evidence to suggest COVID-19 can be transmitted from a corneal transplant, a screening process mitigates any risk.

“Our data assures us that a screening process to determine who’s positive for the virus and who isn’t is important to make sure we do everything in case there is a potential risk of transmission,” Mian said.

Studies have shown that COVID-19 patients hold much of the 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 Mian.

The findings also demonstrate the critical importance of post-mortem nasopharyngeal swab testing for detecting COVID-19 before transplantation.

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