Organ culture preservation for corneal tissue. Technical and quality aspects

The technical and quality aspects of organ culture as a storage method for human donor corneas are described.

Data electronically stored since 1989 of > 41,000 corneas, processed in the Cornea Bank Amsterdam, are analysed. The technical information of eye banks collected in the Directory of the European Eye Bank Association (EEBA) is used as comparison. European Union (EU) directive for tissue banking and EEBA technical guidelines are references for the quality aspects.

Organ culture allows the storage of donor corneas up to 4-5weeks. The storage phase is followed by a generally much shorter phase of 1-7 days, to reverse the corneal swelling occurring in the first phase and to transport the tissue to the clinic. Selection of the corneas based on inspection of the endothelium after storage as well as microbiological testing of the storage solution after a quarantine period are mandatory for this technique. General agreement exists about the outline of the method, but technical variations are applied to suit local circumstances and preferences of corneal surgeons. Agreement exists about a minimum endothelial cell count as selection criterion in case the donor endothelium is meant to be grafted. The use and cutoff points of other selection parameters for the cornea, e.g. the endothelial cell mosaic, are varying. According to EU regulations, a quality management system should be installed. This way each bank is able to issue a standardized product, while the production process is monitored with quality registrations. With the clinical outcome of the graft, the quality of the selection and storage procedures is verified. With the notification of adverse reactions such as primary graft failure and endophthalmitis, minimum risks will be assessed.

The organ-cultured cornea is a well-documented product concerning microbiological safety and quality of the tissue. However, variations in performance and materials and no definite cut-off points for selection do not make an organ-cultured cornea a generally standardized product. The corneal surgeons have to ascertain themselves of the safety and quality of the followed procedure. It is up to an organization such as the EEBA to formulate tissue-specific additions to the EU regulations such as training opportunities, technical guidelines and criteria based on science.