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Covid-19 and the Great Cornea Bank Stickup

That eye banking was hit by the COVID-19 pandemic perhaps won’t come as a shock to most people. Indeed, we’re all painfully aware of just how much it turned the world upside down, so we needn’t further belabor that point. If we can imagine the eye bank as a dusty, small town deposit bank and the virus as a masked, gun-slinging robber, well, that’s not far off. 

The eye banking system in general deserves a closer look vis à vis the virus because there are still some unanswered questions. So, the All India Ophthalmological Society (AIOS) during its first International Ophthalmic Conclave (IOC), or AIOS IOC 2021, turned to Dr. Jennifer Li, professor of ophthalmology and vision sciences at the University of California at Davis and chair of the Medical Advisory Board at the Eye Bank Association of America (EBAA) to shed some light on the situation.

Sand in the Gears

Covid-19 and the Great Cornea Bank Stickup
The pandemic’s sand brought the gears of cornea banking to a halt.

It’s an unusual virus we’re dealing with, to be sure, and extreme caution in eye banking has been the go-to rule. This extreme caution led to what was essentially a complete, worldwide collapse of cornea transplants in March and April of 2020. Just to make that clear, there were for all practical purposes no cornea transplants during that period. That’s unprecedented — another word we’re all likely sick of by now. 

As Dr. Li noted, U.S. eye banks have recovered to around 80-85% of their pre-COVID levels, though international eye banks lag behind. It’s great to see the eye bank world spring back to life, but it’ll take some time before things are running as smoothly as before. We’re not out of the woods yet, anyway. 

Just to chart a clear path through said woods so we don’t get lost, let’s take a quick step back and see how we got to that collapse and then how things have progressed from there. 

Sticky Stuff

Covid-19 and the Great Cornea Bank Stickup
We learned early on that the virus is very hard to get rid of.

Early on in the pandemic, information on just how the virus affected the eyes was scarce. We’ve come a long way, however. The virus behind the pandemic is well known to bind to angiotensin converting enzyme 2 (ACE2) receptors most notably, but others as well. The ACE2 receptor is present in the conjunctiva, limbus and cornea, as are TMPRSS2 and DC-SIGN/DC-SIGNR. Dr. Li pointed out that TMPRSS2 can allow the virus to enter a cell after it’s bound to an ACE2 receptor via its spike protein. Alternatively, the DC-SIGN/DC-SIGNR could be another transmission method for the virus. 

So we know that the virus can infect ocular tissue. That’s the bad news. The good news is that it doesn’t appear to be able to replicate in ocular tissue, or survive there in deceased patients. 

To wit, Dr. Li presented a study by Bayyoud et al.¹ consisting of 10 eyes from 5 patients who had died of COVID-19. Quantitative RT-PCR testing for viral RNA was performed on corneal stroma and endothelium, the bulbar conjunctiva, conjunctival fluid swabs, anterior chamber fluid and the corneal epithelium. 

The result? No viral RNA was detected in any of the ocular tissue or intraocular fluid. So, we’re done here, right?

Not quite. Another, earlier study by Casagrade M. et al.² appears to contradict that notion. Of 11 patients deceased from COVID-19, viral RNA appeared in the corneal tissue of 6 (that’s 55%). The infectivity or structure of the viral proteins couldn’t be confirmed, but it sure left its signature, like a wanted criminal’s calling card. This leaves researchers scratching their heads wondering if the cornea was contaminated via blood or aqueous. 

Gimme a Clue, Doc

Covid-19 and the Great Cornea Bank Stickup
No matter how serious the topic, a dog in a hat is always an appropriate photo choice.

Thus, the sheriff rushed to the scene. The EBAA was quick to consider the implications of the virus in corneal tissue, with discussion beginning as early as January 21, 2020 — just after the first confirmed case in the U.S. The first screening recommendations were sent February 3, 2020, not long afterward. Since then, the guidelines have been continuously evolving and we can likely expect them to evolve further. 

The most recent update was released on October 20, 2020. Crucially, it aims to balance the needs of transplant recipients and doctors with the safety of the donor pool — and there are some good ways to do this. 

Guidelines and Rationale

Covid-19 and the Great Cornea Bank Stickup
The EBAA is helping get the sand out of the gears.

So, for now, we’re left to sort out eligible and ineligible donors. For example, was a deceased person known to be infected with the virus in the last 28 days? They’re not eligible for donation. If they’re negative, or if they were asymptomatic at the time of death? It’s currently not necessary to perform a PCR test to determine if a donor is eligible. They’re good to go. 

Before you get concerned, the rationale here is that this relies on a more decentralized system, anchored by the medical expertise of the people on the scene. An overall increase in testing has led to improved screening, and local medical directors are more capable of making decisions regarding the safety of donor tissue than before. In some cases, still, a negative PCR test may be required to check some corneal tissue. 

Ocular inflammation, like conjunctivitis, keratitis, and so on, is a contraindication for harvesting corneal tissue. That’s a no-go. 

In the event tissue has been deemed safe to harvest, it must be washed at least twice with a 5% povidone-iodine solution between the time of the donor’s death and tissue harvesting. 

What happens when things go wrong?

In the event that, somehow, infected corneal tissue is transplanted to a recipient, it’s not the end of the world. This has in fact happened, but no one has been harmed by it. 

As far as we know right now, there’s no indication of COVID-19 transmission from corneal tissue. Dr. Li noted there are currently eight known cases of accidental transplant of tissue from donors infected with the virus at the time of their death. Of these eight cases, the recipients are all fine: They did not develop COVID-19 during the postoperative period and all the grafts were successful. So, hey, even when mistakes happen, people somehow come out of it okay. Thank goodness for that.

Editor’s Note: AIOC IOC 2021 was held virtually on February 19 to 21. Reporting for this story took place during the event.

References: 

1 Bayyoud T, Iftner A, Iftner T, et al. Absence of Severe Acute Respiratory Syndrome-Coronavirus-2 RNA in Human Corneal Tissues. Cornea. 2021;40(3):342-347. 

2 Casagrande M, Fitzek A, Püschel K, et al. Detection of SARS-CoV-2 in Human Retinal Biopsies of Deceased COVID-19 Patients.Ocul Immunol Inflamm. 2020;28(5):721-725. 

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