Cornea Procurement and Processing up to 72 Hours: No Risk for Cornea Transplant Quality.

BACKGROUND: The realization of tissue donations is bound to a tight timeframe. Depending on the type of tissue, time limits are specified within which the donation must be procured and processed. Otherwise, there is a risk of tissue quality loss with increasing time intervals from cardiovascular arrest. According to the European Directorate for the Quality of Medicines and HealthCare (EDQM) guide, cornea must be procured and processed within 72 h after death. The question arises whether this time interval has an influence on the quality of transplanted tissues and how it affects the accomplishment of tissue donations. METHODS: In order to obtain information on this, the numbers of tissue donations in the network of the German Society for Tissue Transplantation (DGFG) were evaluated as a function of the death to retrieval time (DRT) as well as the death to preservation time (DPT). For this purpose, 21,454 database entries of cornea donations made in the period from 2014 to 2018 were included. RESULTS: The results show that nearly 50% of donations realized in the DGFG network could be processed only 48 h or later after cardiovascular death due to the opt-in regulation in Germany. For these donations, there seems to be a higher discard rate compared to donations taken earlier. Nevertheless, there is a transplantation rate for these grafts of more than 65%, which is comparable to average transplantation rates stated in the literature. CONCLUSION: All corneas finally selected for transplantation must meet the specified quality parameters. Since this naturally also applies to transplants that could only be procured at later time points, it can be concluded that DPT up to 72 h for corneal tissue is adequate and has no influence on the quality of corneas that are ultimately transplanted.

Risk of SARS-CoV-2 virus transmission from donor corneal tissue: A review.

Since the outbreak of respiratory coronavirus disease (COVID-19) caused by the coronavirus SARS-CoV-2, there is an ongoing discussion about whether the virus could be transmitted through corneal transplantation from donor to recipient. The purpose of this review was to summarize the current knowledge in the scientific community to provide aid in risk evaluation for potential virus transfer by corneal transplants. Literature was searched in PubMed.gov for relevant articles on coronavirus in conjunction with cornea processing, cornea transplantation and eye banking. Further, guidelines of health authorities and eye banking associations were reviewed. Studies have shown that SARS-CoV-2 RNA can be detected in ocular swabs and/or fluid of patients with COVID-19. However, the risk of SARS-CoV-2 virus transmission through these ocular tissues or fluid of patients is judged differently. To date, per literature and official guidelines, no evidence of viable virus in ocular tissue and no cases of transmission of SARS-CoV-2 via tissue preparations have been reported.

SARS-CoV-2: Impact on, Risk Assessment and Countermeasures in German Eye Banks.

INTRODUCTION: Since the beginning of the COVID-19 pandemic there has been some debate regarding the risk of transmission through tissue transplantation and tissue banking processes. AIM OF THE STUDY: To analyze the changes that SARS-CoV-2 has caused regarding the harvesting of corneal donor tissue and eye bank activities in Germany. METHODS: A questionnaire was provided to 26 eye banks in Germany, consisting of questions about adaptations made in the screening of potential donors and the harvesting of corneal tissue following the pandemic spread of SARS-CoV-2. RESULTS: Eighteen eye banks actively reduced recruitment of donors and two banks ceased all activity. Additional diagnostic screening was performed in eight banks, using conjunctival swabs and/or nasopharyngeal swabs. In six eye banks, additional protective measures, such as FFP2 masks and/or facial shields, were implemented. Overall, a mean reduction in the number of obtained donor tissues of 17% was observed. DISCUSSION: Conjunctival and/or nasopharyngeal swabs of donors have been implemented by a minority. Reasons for not performing additional tests may be moderate sensitivity and lack of validation for postmortem use of RT-PCR testing. Also, the hazard of SARS-CoV-2 entering the corneal donor pool with subsequent transmission might be perceived as theoretical. Face shields provide a sufficient barrier against splash and splatter contamination but may be insufficient against aerosols. Additional face masks would provide support against aerosols, but it remains debatable if corneal harvesting can be considered an aerosol-producing procedure. In the future we expect to see changes in current guidelines because of a surge in scientific activities to improve our understanding of the risks involved with cornea donation in the COVID-19 pandemic, and because current practice may reduce the availability of donor corneas due to new exclusion criteria while the demand remains unchanged.