Eye banks, corneal surgeons tackle hand in hand evolving challenges of pandemic
Donor selection is well balanced between ensuring safety and allowing enough tissue to meet the needs of surgeons.
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As elective corneal transplantation procedures resume, eye banks continuously monitor the evolution of the COVID-19 pandemic and update their guidance and screening recommendations, while cornea practices enhance safety measures.
“Between the end of March and the end of April, domestic surgery was down to 6% to 7% of normal volume. By the beginning of June, the volume for corneal transplantation had gone back to 70% and further increased to 80% by the beginning of July. It was a very quick shutdown but a relatively rapid reopening as well,” Jennifer Y. Li, MD, medical director of Sierra Donor Services Eye Bank and medical advisory board chair of the Eye Bank Association of America (EBAA), told Ocular Surgery News.
At the beginning of the pandemic, the EBAA released strict precautionary COVID-19 screening recommendations for member eye banks.
“There was little information at the time about this novel virus and lots of concerns. Not only were we all concerned about the unknown potential for donor-recipient viral transmission, but there were also concerns about the safety of our eye bank staff and their risk of exposure to the virus in the process of recovering and processing of tissue. At the time, donor screening criteria relied heavily on symptoms, which are unfortunately very nonspecific. As a result, we experienced a significant decrease in eligible donors. Fortunately, this decrease in donors corresponded to the decrease in surgical volume from stopping elective corneal transplantation procedures,” Li said.
The conservative criteria for donor selection unintentionally helped to create the right balance between supply and demand, avoiding tissue wastage. U.S. eye banks use cold storage in Optisol-GS (Bausch + Lomb) or Life4C (Numedis), which preserves them for a relatively short period, up to 14 days.
“In my eye bank, we further adjusted our own criteria for recovery to avoid tissue wastage and made a conscious effort to recover just enough tissue to meet the demand. We want to be able to respect the wishes of the donor and the donor family when we recover tissue. Since most of corneal transplantation surgery was deferred, there was the risk of procuring excess corneal tissue that we would not be able to use or export,” Li said.
Evolving guidelines
Since then, the EBAA committee has met on a regular basis to update its recommendations based on the information, data and progressive experience with COVID-19. Four iterations of the guidelines were released, an evolving process that closely followed the evolution of the pandemic. As elective surgical procedures started to resume, the guidelines were changed to help widen the pool of potential donors.
“We are constantly trying to balance safety of the donor pool while allowing for enough tissue to meet the needs of our surgeons,” Li said.
Donor eligibility is based on previous close contact with COVID-19 cases and premortem COVID-19 signs and symptoms that include respiratory infection, loss of taste and smell, fatigue, muscle and body ache, and gastrointestinal symptoms. EBAA does not recommend postmortem RT-PCR testing because of the high rates of false negatives and positives and because RT-PCR tests for SARS-CoV-2 are not validated for cadaveric donors.
“The other concern is that postmortem testing would delay the distribution of tissue since it can take several days for test results to come back. However, if patients were previously screened for COVID, this can help determine donor eligibility,” Li said.
With 28,402 corneas exported internationally in 2019, the U.S. is the main global supplier for countries where there is a shortage of corneal tissue. The pandemic, however, has cut down international distribution to under 3% of the normal supply.
A cautious approach to surgery
So far, there have been no reported cases of transmission of SARS-CoV-2 or other coronaviruses via transplantation of ocular tissue, but transmission of viruses through transplantation has been always a major concern for surgeons and eye banks.
“For this reason, viruses are well represented in the exclusion criteria for corneal donation. We exclude HIV, although, interestingly, there has never been a documented case of HIV transmitted by corneal transplantation, whereas there are cases of AIDS transmitted by other tissue allografts, such as heart, kidney and liver. It is questionable whether anybody had hepatitis C from corneas, either. On the other hand, rabies and mad cow disease are transmitted by corneas. If we have an unknown cause of death, especially neurologic, we don’t use those corneas,” OSN Cornea/External Disease Board Member Francis W. Price Jr., MD, said.
COVID-19, he said, has cut down on the availability of corneal tissue for transplantation, but this has gone hand in hand with the decreased volume of transplantation surgeries performed.
“We went back to work at the end of April, but DMEK volume is not quite back to what it was. Only PK volume is the same as it was before because most of those cases have ulcers or infections. Some patients are still reluctant to come to the clinic for fear of infection. One of my patients who was scheduled for surgery said he wants to wait until November, but I warned him that the risk is likely to be higher in the autumn and winter season,” Price said.
Strict safety measures
Strict safety measures have been adopted in the clinic. Patients come alone according to scheduled appointments to avoid having people in the waiting area, where chairs are now fewer and well distanced. Everyone wears masks, staff and patients, and the whole office and examination rooms are routinely disinfected in between patients.
“To cut down on the time the patient is in the office, we collect the patients’ histories and other information ahead of time over the telephone,” Price said.
In the surgery center, in the preop/postop area, there are now half the usual number of beds. The air is purified using a special ultraviolet air treatment system, and a hydroxyl generator safely kills viruses, bacteria and other pathogens in indoor air.
In his practice at Price Vision Group in Indianapolis, Price has decided not to perform COVID-19 testing before surgery.
“First, because our surgical procedures are pretty quick with either topical or local anesthesia, there is less risk to patients and staff than with general anesthesia, and our routine disinfection protocols reduce the risk of contamination. In addition, I have seen people waiting up to 2 weeks to get their results back, and the rate of false negatives is about 30%. With that and having to tell the patients to self-quarantine for 72 hours after a test, we think that testing is not practical at this time. Hospitals are doing it, and some of the states in the U.S. require it, but it is not required in our state,” Price said. “We need to take all regular precautions, and eye banks have to do their job at screening the donors, and right now corneal transplantation surgery is not a big problem. Of course, the recent FDA approval of a $5 antigen test that provides results in 15 minutes and that can be quickly scaled up to production of tens of millions of test kits per month could be a major game-changer in terms of routine presurgical testing.”
The real problem is going to be this winter, he believes, when colds and flu will start, and symptoms may be confused with COVID-19 symptoms.
“It is going to be a problem not just for the patients but for our staff. Anyone who wakes up with a sore throat or respiratory symptoms will not come to work because it could potentially be COVID. It is going to be a mess. Talk to me in December, and I might have to tell you a different story,” he said.
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For more information: - Jennifer Y. Li, MD, can be reached at UC Davis Eye Center, 4860 Y St., Suite 240, Sacramento, CA 95817; email: jyhli@ucdavis.edu.
- Francis W. Price Jr., MD, can be reached at Price Vision Group, 9002 N. Meridian St., Suite 100, Indianapolis, IN 46260; email: fprice@pricevisiongroup.net.
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