For corneal donation programs to maintain consistent levels of tissue, there needs to be a relatively steady reserve from suitable donors. As health care agencies in Europe adapted to the SARS-CoV-2 pandemic, policies developed with the goal of safe transplantation varied widely, and in 2020 a dramatic decrease occurred for donated corneas collected and distributed throughout the continent.

During potential future pandemic surges, more standard testing at the time tissue is gathered may be needed to maintain uninterrupted sight-saving procedures — for example, PCR on nasopharyngeal swab for donors with respiratory symptoms, reports an analysis published in the British Journal of Ophthalmology. “Moreover, while the USA and most European countries are self-sufficient, stringent exclusion criteria are likely to jeopardize transplant programs in countries relying on imports,” the study noted. Investigators analyzed corneal supply and allocation from February 2018 to May 2020 — examining questionnaire data from 64 eye banks that represent 95% of Europe’s corneal tissue activity, and comparing protocols of each country and the European Center for Disease Prevention and Control. Data was controlled for each nation’s pandemic severity, represented by cases and deaths.

Acquired tissue declined in 2020 by 38% in March, 68% in April, and 41% in May compared with the mean of this trimester in the 2 years prior. Similarly, grafts decreased in 2020 by 28% in March, 68% in April, and 56% in May. This reduction affected 3866 untreated individuals. Further, significant differences in activity among eye banks occurred, as well as large variations in donor selection algorithms between countries. In fact, the negative correlation between strictness of donor suitability and acquisition of corneas was significant (P <.01), and “COVID-19 deaths had very little influence in controlling for the relationship between the decrease in procurement and stringency.” 


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National differences included diverse eligibility requirements for donors suspected of having COVID-19, and for individuals who survived but then died from another illness. Symptoms considered for COVID-19 infection varied, as did what constituted risk from asymptomatic individuals. Also, PCR testing procedures were not standardized, and only Italy had guidelines to perform serology (for epidemiological purposes). However, all countries excluded tissue from patients who died from the coronavirus.

While it is known that some pathogens which trigger local infection can be transmitted by corneal transplant — bacteria, herpes simplex, and fungi — systemic viruses are not typically spread by the cornea because it exhibits strong surface immunity and no blood or lymphatic vessels. Further, after the tissue is acquired, it is most often treated with povidone-iodine. 

There is no known corneal transmission of airborne respiratory illness. Previous studies have demonstrated contradictory results for whether the coronavirus is associated with conjunctivitis, or can be transmitted via tear outflow.

The analysis notes donation rates may have been affected by a decline in elective surgeries, as well as deaths not in a hospital that may have been indirectly related to the coronavirus; and these factors may limit results of the investigation. A strength is the high eye bank response rate — 83% from the total 110 eye banks in 26 European countries. This is the first study concerning COVID-19’s impact on corneal transplantation patterns affecting multiple nations.

Reference

Thuret G, Courrier E, Poinard S, et al. One threat, different answers: the impact of COVID-19 pandemic on cornea donation and donor selection across Europe. Br J Ophthalmol. 2022;106:312-318. doi:10.1136/bjophthalmol-2020-317938