EBEI: A new index of eye bank efficiency

Purpose: To describe a new proxy of the Eye Bank (EB) activity named "Eye Bank Efficiency Index" (EBEI), calculated as the ratio between the number of corneal tissues distributed by an EB within a certain time period, and the difference between the number of procured and discarded tissues. Methods: To demonstrate the effectiveness of the new metric as compared to traditional statistics, an analysis was conducted using data from the largest Italian Eye Bank (Fondazione Banca degli Occhi del Veneto Venice, Italy). Collected data included: the number of corneas retrieved, the number of discarded grafts, and the number of distributed tissues. The analysis focused on three defined timeframes: January to December, March to May (the "Italian Lockdown period"), and June to December (the "Italian post-lockdown period"). Results: In 2020, the annual variation of the EBEI showed a significant increase of up to 3.4% compared to the previous year (0.986 in 2019; 1.020 in 2020), but then gradually decreased to 0.993 in 2022. However, during the months of lock-down in 2020, there was a significant decline of -13.8% in the EBEI compared to the same period in the previous year. The variation in the EBEI during the post-lockdown months was minimal in 2020 and 2021, with the lowest EBEI value of 0.976 being reached in 2022 (-7.8% compared to 2019). Conclusion: The EBEI is a simple and reliable new measure of the EB activity. Its widespread adoption could ensure a more accurate and reliable analysis of EB data for academic, political, and economic purposes.