Deep Anterior Lamellar Keratoplasty (DALK)
DALK is the transplantation of a donor cornea without its lowest double-layer Descemet's and Endothelium to the recipient's cornea. On this tissue the upper 90% of the diseased tissue is removed. In about 70% of corneal scars and other diseases these two layers of the recipient stay in order, so that the patient would not need a transplantation of all layers but only of the upper 90%. So the most inner layer of the cornea, the Endothelium, taking care of the Oxygen supply of the cornea remains intact. Immediately after the operation, the Epithelium grows over the newly transplanted tissue, which happens in 4-5 days which then leads to the situation that the upper and the inner layer are tissue of the patient himself and only the tissue in between is sandwich-like the foreign tissue. The big advantage of this method is, that the eye is not opened and that only the scarred or diseased tissue is removed. Complications are greatly reduced using this procedure.
In particular DALK may be seen as definite healing of the corneal disease as one does not have to envisage further transplantations or that the tissue may be rejected. In a Penetrating Keratokplasty(PKP) the life of the transplant can be foreseen for only 10-15 years as the most inner layer, the Endothelium, is slowly destroyed so that the transplant then becomes intransparent. So with PKP the implication is that one has to repeat the operation after this period of maximally 15 years. Beside, in a PKP occurrene of immune reaction is at least 6%, in DALK it is 1%. An exact analysis of these data may be read in this publication. Conducting DALK is the most difficult operation of the anterior segment of the eye. We have made DALK even saver by introducing the Water-Pillow-Technique, which is successful in 95% of all cases. For this purpose the here developed Guided Trephined System is used allowing removal of the upper diseased layers with an accuracy of 20µm (2/100mm).