Eyeworld

DECEMBER 2020 | EYEWORLD | 111 C About the sources Winston Chamberlain, MD, PhD Petti Associate Professor of Ophthalmology Casey Eye Institute Oregon Health & Science University Portland, Oregon Clara Chan, MD Department of Ophthalmology University of Toronto Toronto, Canada Kevin Corcoran President and CEO Eye Bank Association of America (EBAA) Washington, D.C. Jennifer DeMatteo Director of Regulations and Standards Eye Bank Association of America (EBAA) Washington, D.C. continued on page 112 Patient-ready DMEK tissue Source: EBAA A study of 33 donor corneas that were excluded from surgical use due to not meeting EBAA screening guidelines, medical director review, or a positive COVID-19 test found that of the 20 eyes that came from donors who were positive for COVID-19, three conjunctival swabs, one anterior corneal, five posterior corneal, and three vitreous swabs were positive for the viral RNA. 1 The researchers also detected SARS- CoV-2 spike and envelope proteins in corneal epithelium in eyes that were not disinfected with povidone-iodine. The authors of the pre- press study concluded that there is a "small but noteworthy prevalence of SARS-CoV-2 in ocular tissues from COVID-19 donors," which high- lights the importance of donor screening guide- lines, post-mortem testing, and povidone-iodine disinfection. A paper by Desautels et al. on the topic of donor corneal tissue said, "Current recommen- dations from the United States and global eye bank associations call for the outright avoidance of tissues from donors recently infected with or exposed to COVID-19. This conservative recom- mendation is currently appropriate given the reported ocular sequelae, tear film viral detect- ability, and transmissibility of COVID-19." 2 "Several reports have suggested low probability of infectious viral particles in ocular tissue, but real data on risk of transmission from an infected donor are still not known," Dr. Chamberlain said in a follow-up email to EyeWorld. He pointed to a 2006 study that found ACE2, the host cell receptor that binds SARS-CoV envelope spike protein, in the cornea and conjunctiva. The authors concluded that these cells can bind to the viral spike proteins "slightly." 3 Jennifer DeMatteo noted that, per the FDA, coronaviruses are not known to be transmitted by transplantation of human cells, tissues, or cellular or tissue-based products. "There have been no reported cases of transmission of SARS-CoV, MERS-CoV, or any other coronavirus via transplantation of ocular tissue," she said. As such, she explained that current EBAA standards require double exposure of povi- done-iodine to the entire surface of the ocular tissue, resulting in rapid viricidal activity against coronaviruses and reduced likelihood that COVID-19 may be transmitted through corneal transplantation. The EBAA has funded research that will analyze regional infiltration of SARS- CoV-2 in ocular tissues and evaluate the efficacy of povidone-iodine to inactivate the virus within ocular tissue of COVID-19 positive donors, Ms. DeMatteo said. This research will also assess the impact of the pandemic on donor referrals. A second grant from EBAA is funding research that looks at whether the virus can be transmit- ted through donor corneal tissue. At this time, to ensure safety of donor tissue, Ms. DeMatteo said eye banks should exclude potential donors who are diagnosed with or suspected to have had COVID-19 or close contact with someone with COVID-19 in the past 28 days. The EBAA released a donor eligibility matrix specifically for COVID-19. "At this time, the EBAA is not requiring eye banks to perform post-mortem nasopharyngeal RT-PCR testing for SARS-CoV-2. However, a neg- ative PCR result may be necessary (in addition to a medical director review) to release tissue from donors with another etiology to explain their signs and symptoms," she continued, add- ing that diagnostic RT-PCR tests for SARS-CoV have not been validated for cadaveric donors and are not intended for donor screening. "The FDA does not currently recommend the use of laboratory tests to screen asymptomatic HCT/P donors."

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