Purpose: To measure corneal endothelial cell (EC) quality and quantity following Descemet membrane (DM) stripping of human donor corneas and continued storage in organ culture medium containing dextran. Methods: DM stripping was performed in 30 organ cultured, corneoscleral discs. Corneas were divided into 3 groups of 10 corneas each. Baseline mean EC density (cells/mm²) was 2,372 (SD ± 259) in group 1, 2,540 (SD ± 266) in group 2, and 2,665 (SD ± 263) in group 3. Following subtotal DM stripping, culture was continued at 31°C for 24 hours (group 1), 72 hours (group 2), and 120 hours (group 3), respectively. EC density was measured before stripping and at the end of culture. At the end of culture, corneal EC morphology was graded using a scoring system and EC viability was measured by detection of adenosine triphosphate. Results: At the end of culture, mean EC density was 2,159 (SD ± 293) in group 1, 1,946 (SD ± 182) in group 2, and 2,047 (SD ± 225) in group 3. This constitutes an EC loss of 9,1% (SD ± 5,3%) in group 1, 23,0 % (SD ± 6,5%) in group 2, and 22,7% (SD ± 9,1%) in group 3 (p < 0.001). After completion of follow-up, all groups contained corneas with EC counts < 2,000 cells/mm². Cell morphology scores did not differ between the three experimental groups. EC viability measurements showed a tendency toward lower readings with extended length of culture. Conclusions: Corneal EC loss does occur following DM stripping and continued organ culture. EC loss increases with storage past 24 hours, but donor corneas may fall below 2,000 cells/mm² independently of storage duration. The use of eye bank prepared donor lamellae for Descemet Membrane Endothelial Keratoplasty (DMEK) may increase patient safety by offering standardized quality control before tissue release.

Human amniotic membrane (hAM) is usually stored at −80 °C. However, in many regions, cryopreservation at −80 °C is not feasible, making hAM unavailable. Therefore, the possibility of cryopreservation at −28 °C (household freezer) was investigated. hAMs (n = 8) were stored at −80 °C or −28 °C for a mean time of 8.2 months. hAM thickness, epithelial integrity and basement membrane were assessed histologically. The collagen content, concentration of hepatocyte growth factor (HGF) and basic fibroblast growth factor (bFGF) were determined. Elastic modulus and tensile strength were measured. The mean thickness of hAM stored at −28 °C was 33.1 ± 21.6 µm (range 9.7–74.9); thickness at −80 °C was 30.8 ± 14.7 µm (range 13.1–50.7; p = 0.72). Mean collagen content, epithelial cell number and integrity score showed no significant difference between samples stored at −28 °C or −80 °C. Basement membrane proteins were well preserved in both groups. Mean tensile strength and elastic modulus were not significantly different. Concentration of bFGF at −28 °C was 1063.2 ± 680.3 pg/g (range 369.2–2534.2), and 1312.1 ± 778.2 pg/g (range 496.2–2442.7) at −80 °C (p = 0.11). HGF was 5322.0 ± 2729.3 pg/g (range 603.3–9149.8) at −28 °C, and 11338.5 ± 6121.8 pg/g (range 4143.5 to 19806.7) at −80 °C (p = 0.02). No microbiological contamination was detected in any sample. The cryopreservation of hAM at −28 °C has no overt disadvantages compared to −80 °C; the essential characteristics of hAM are preserved. This temperature could be used in an alternative storage method whenever storage at −80 °C is unavailable.

Aim To determine whether clinical performance is negatively affected by prestripping Descemet membrane endothelial keratoplasty (DMEK) grafts from organ-cultured corneas. Methods We reviewed clinical records of all patients who underwent DMEK surgery for Fuchs endothelial dystrophy between 28 October 2014 and 11 August 2015. Grafts had been prepared from organ-cultured corneoscleral buttons 24 hours prior to surgery or during surgery. We included only patients for which at least one follow-up examination was available at a minimum of 2 months postoperatively. Main outcome measures: best-corrected visual acuity (BCVA), central corneal thickness, endothelial cell count and rebubbling rates. Results Data given are mean±SD. No statistically significant differences were recorded at baseline between the partially stripped group (n=65) and the control group (n=72) with regard to donor age (70±9 vs 69±8 years; p=0.49), donor cornea endothelial cell density (2586±604 vs 2522±186 cells/mm²; p=0.6), BCVA (before DMEK: 0.77±0.5 vs 0.63±0.3 logMAR; p=0.27; before triple-DMEK: 0.56±0.2 vs 0.52±0.2 logMAR; p=0.33) or central corneal thickness (621±72 vs 607±53 μm; p=0.49). Mean follow-up was 149±83 versus 148±77 days; p=0.79. No statistically significant differences were observed between the two groups postoperatively with regard to BCVA (after DMEK: 0.25±0.2 vs 0.21±0.2 logMAR; p=0.59; after triple-DMEK: 0.22±0.2 vs 0.2±0.1 logMAR; p=0.98), central corneal thickness (502±42 vs 508±41 μm; p=0.47), endothelial cell count (1537±245 vs 1551±287 cells/mm²; p=0.65) and number of graft detachments requiring rebubbling (4.6% vs 9.7%; p=0.33). Conclusions We found no evidence that the use of prestripped DMEK grafts is inferior to same-day preparation in organ-cultured corneas within the given follow-up.

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. To analyze the changes that SARS-CoV-2 has caused regarding the harvesting of corneal donor tissue and eye bank activities in Germany. 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. 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. 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.