CHANGES IN HUMAN DONOR CORNEAS PRESERVED FOR LONGER THAN 4 WEEKS

Purpose. Corneas are usually stored for a maximum of similar to 30 day s in European cornea banks. Although attempts are being made to prolon g culture periods, data on their success are extremely limited to date . The following study was carried out to describe the capacities and l imits of the established system. Methods. Thirty-seven human corneas w ere stored for less than or equal to 12 weeks under standard eye bank conditions [modified minimal essential medium (MEM), 31 degrees C, clo sed system]. Twenty-one fresh human corneas served as control. Both th e adenylate nucleotides and the glucose and lactate concentrations wer e measured in the tissue (all cellular layers) by using the biolumines cence technique. The endothelial-cell densities also were determined. Results. Endothelial-cell densities decreased from 2,963.4 +/- 58.7 ce lls/mm(2) (fresh) to 2,649 cell/mm(2) after 4 weeks and to 2,087 cells /mm(2) after 6 weeks. Storage for periods >6 weeks led to total endoth elial necrosis. Biochemical studies showed improving values during the first 4 weeks and acceptable conditions for less than or equal to 6 w eeks. Conclusion. From these data, we conclude that long-term organ cu lture in a closed system is limited to similar to 6 weeks and thereby confirm the clinical results of Fruh and Bohnke.