B.2.1.1. Access to the operating room or other recovery room
See generic requirements in section A.4.1.1.
See generic requirements in section A.126.96.36.199.
Except for the room, the entire retrieval of the donor cornea and sclera is to be performed analogous to ophthalmic surgery in a living patient. Retrieval may be either by removal of the whole eye (enucleation) or by removal of only the corneoscleral button (in situ excision). Tissue recovery is to be performed using validated aseptic procedures.
Prior to tissue recovery, the donor should be positively identified by cross-check with a tag or other label on the body, or by positive identification by hospital or mortuary staff.
Staff performing the retrieval is to be dressed appropriately for the kind of retrieval to minimize the risk of contamination of the tissue to be removed and also the hazard for the performing staff. This includes due disinfection (surgical hand disinfection), sterile clothes as well as wearing sterile gloves, face mask or protective mask and surgery cap.
The donor eyes should be flushed with a balanced sterile saline solution to remove all debris, mucus and foreign matter from the cornea and conjunctival sack. Irrigation will also reduce microbial contamination. A broad-spectrum antibiotic / antifungal ophthalmic solution may be used for further moistening the eyes. Subsequent to an effective disinfection of donor skin in the eye area and conjunctiva using a suitable disinfectant (e.g. PVD iodine), a local sterile area is to be created in the area of retrieval using sterile cloths. Hereafter, either the whole eye or the corneoscleral disc is to be recovered. The recovery methods are described in Section A.4.
Enucleation should be performed analogous to ophthalmic surgery in a living patient. After enucleation, the bulbus should be placed in a fixed position (avoiding contact with the cornea and the container) in a moist chamber with sterile physiological electrolytic solution (see 2.3.5). Broad-spectrum ophthalmic antibiotic drops may be used to further minimize bacterial contamination. Containers with the eye should be secured tight and labelled.
The appearance of the donor is to be restored using appropriate prostheses or other material suitable for this purpose. Also any visible disinfection solution is to be wiped off from the donor’s skin. And when needed, the donor lids should be closed by tissue glue.
Corneoscleral disc in situ excision should be performed analogous to ophthalmic surgery in a living patient. Peritonomy should be performed to incise the conjunctiva in a circle as close to the limbus as possible. Sclerotomy should be performed by making an incision through the sclera 2-3mm from the limbus. Care should be taken not to penetrate the underlying choroid. Any trauma and stress to the cornea during incision and scissoring, as well as during the subsequent ciliary body detachment should be avoided.
After in situ excision the corneoscleral disc should be immersed in an appropriate corneal storage solution. And when needed, the donor lids should be closed by tissue glue.
Scleral tissue should be recovered from a whole eye on whole eye retrieval by enucleation).
See generic requirements in section A.4.1.4.
See generic requirements in section A.5.1.4.
See generic requirements in section A.4.1.5.
Subsequent to retrieval, the obtained donor corneas or eyes are to be packaged in a way to minimize the contamination risk. Each tissue is to be packed separately in separate containers and labelled immediately after recovery.
The organ culture system provides a functional assessment of the cornea during the prolonged storage time (compared to the hypothermic storage).
For subsequent packaging of corneoscleral complex, tissue banks should use a sterile, air tight sealable container containing appropriate normothermic corneal storage medium in accordance with manufacturer’s recommendations. The culture medium is an essential factor to guarantee the quality and safety of the donor cornea. For this reason, an established medium for the purpose of corneal preservation is to be used (e.g. MEM). The addition of foetal calf serum is only permissible under the folowing preconditions:
a) Serum from ‘BSE free’ livestock (manufacturer’s certificate);
b) Negative test result for mycoplasma;
c) Sterile filtered serum.
For packaging for hypothermic storage of a corneoscleral disc, tissue banks should use an air tight sealable container containing hypothermic corneal storage medium (e.g. OptisolGS) in accordance with manufacturer’s recommendations. The medium is to maintain the endothelial cell morphology and thinness of the cornea.
An enucleated eye is to be placed in a sterile, air tight sealable chamber together with gauze, moistened by physiological electrolytic solution or antibiotic solution, and then placed at 4ºC. The eye must not be immersed in solution as it will be absorbed by the cornea and cause stromal oedema.
Scleral tissue is part of the whole eye and, after whole eye recovery, should be packaged accordingly (see B.188.8.131.52.3. Whole eye packaging / Moist chamber storage).
Eye banks should use an appropriate package and cryopreservation medium in accordance with regulatory requirements.
See generic requirements in section A.4.1.6.
The donor eyes / corneas are to be stored at temperatures appropriate to maintain their characteristics and biological functions suitable for the intended operation. These temperatures principally correspond to the storage temperatures specified below independent of the method of cultivation.
a) The donor corneas obtained for organ cultivation by corneoscleral complex excision should be stored in organ culture medium at temperatures from +10 to +40°C.
b) The donor eyes and corneoscleral discs for hypothermic storage / moist chamber storage should be stored cold at temperatures between +1° and +10°C (e.g. using cooling elements). Temperatures below 0°C are to be strictly avoided.
c) Corneas for cryopreservation for long-term storage (intended for the purposes of tectonic (structural) keratoplasty only) should be stored by freezing at sub-zero temperatures between -75ºC to - 196ºC. It must be recognized that the functional integrity of the corneal endothelium will be lost, and eye banks may elect to remove the endothelium before storage by this method.
Corneas typically must be transplanted as a viable living tissue. The aim of any current corneal storage technique (except cryopreservation) is simply to maintain this living viable state while holding the cornea for the period between donation and transplantation. Maximum storage time of ocular tissues in organ culture or hypothermic solution depends on the storage medium used. The storage time should not exceed the maximum storage time prescribed by the medium / solution manufacturer, or the maximum storage time determined by the tissue bank validation process. Recommended maximum storage times are presented below.
A minimum storage period is mandatory to allow for proper microbiological testing of the tissue, or the solution in which the tissue is stored. The efficacy of this quarantine period should be evaluated and validated.
B.184.108.40.206.2.1. Organ culture
The maximum recommended storage time by organ culture is 30 days (depending on the medium used) but the storage time may be extended upon the approval of the Medical Director and agreement with the transplanting surgeon.
B.220.127.116.11.2.2. Hypothermic storage
The maximum recommended storage time in hypothermic storage where a viable endothelium is required is 14 days (depending on the medium used) but this may be extended upon the approval of the Medical Director and agreement with the transplanting surgeon. A longer period is acceptable if the endothelium does not need to be viable which should be decided by the Medical Director.
B.18.104.22.168.2.3. Whole eye
The maximum recommended storage time of whole eye in moist chamber storage is 48 hours. However, the time may be extended upon the approval of the Medical Director and agreement with the transplanting surgeon.
B.22.214.171.124.2.4. Corneal cryopreservation
The maximum recommended storage time by corneal cryopreservation is two years. However, this may be extended upon the approval of the Medical Director and agreement with the transplanting surgeon.
B.126.96.36.199.2.5. Scleral tissue
After recovery the scleral tissue is part of the whole eye and should be stored accordingly.
The donor eyes / corneas are to be transported at appropriate temperatures to maintain their characteristics and biological functions. Principally these temperatures correspond to the storage temperatures (see chapter B.188.8.131.52.1), depending on the tissue and the method of cultivation.
The package and the mode of transport are to be chosen in a way as to ensure maintenance of the tissue specific storage temperatures (see chapter B.184.108.40.206.1). This is to be monitored by the tissue bank at regular intervals. If temperature stability should not be reliably guaranteed by the pack or mode of transport used, also in cases of unexpectedly high or low environmental temperatures, a temperature recording unit is to be enclosed that is to measure the temperature inside the pack in minimally half-hour intervals and the data saved. In addition, the pack is to prevent contamination by persons in charge of tissue packaging and transport.
The transport time of donor placentas should be kept as short as possible.
See generic requirements in section A.4.1.7.