Purpose One of latest surgical development of preloaded Descemet membrane endothelial keratoplasty (DMEK) is the delivery of the graft with the endothelium inwards, which allows for a very fast operation, but requires a pull-through surgical technique. Although the tri-folded, endo-in DMEK technique has significant advantages, the absence of proper surgical instruments that could allow their use without the ‘pull-through’ technique still restricts the wide use of such an operation. None of the available commercial DMEK injectors could be used for tri-folded DMEK (endothelium-inward) orientation, as it requires the graft to be intently secured within the injector. This report presents a retrospective eye bank validation study of an asymmetrical injector designed to orientally implant a tri-folded DMEK graft without needing a pull-through technique.
Methods The injector is made from transparent plastic, allowing microscopic tissue validation directly before injection. The device is asymmetrical, so the orientation of the graft can be controlled and validated according to the best eye bank practice, which is critical for successful tri-folded DMEK graft clinical application. Four different designs of the internal compartment of the injectors were evaluated with DMEK tissues. Mates from two pairs were tested on each device type, totaling 16 grafts, all loaded with folded, endo-in grafts. The tissue was prepared, loaded into the injector, and ejected to imitate the tissue manipulation in DMEK operation.
Results After graft loading the delivery of the endothelium-in grafts was performed by injection, without the need for a pull-through technique. One graft (6.25%) has double-scrolled (changed its folding) within the injector with a larger (1.5 mm) internal compartment. The loss of valuable cells was between 3-23% (13.98% average). No significant differences in cell loss were observed between injectors with different internal compartment sizes. Higher viability loss (17.3% +/- 5.7) was observed for the grafts with >20 days death to prep-days in comparison with grafts stored with less than two weeks (10.9% +/-2.1).
Conclusion The TissueGUARD injector is the only injector that currently allows oriented, tri-folded DMEK injection without the need for a pull-through technique. The average cell loss after loading and ejection was 13.98%, which is comparable/better than the current best practice with the precut-preloaded technique of naturally folded DMEK.
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