S- or F-stamping donor tissue for Descemet’s membrane endothelial keratoplasty is widely practiced to guard against DMEK’s most embarrassing potential complication: accidental upside-down graft implantation.
These orientation marks are so common, in fact, that many DMEK surgeons have never even attempted the operation without them. However, the originally described DMEK technique was stamp-free, and that is still the way the operation is performed today at the Netherlands Institute for Innovative Ocular Surgery, where DMEK was invented. So, rather than a necessary feature, tissue