In case there is no high shortsightedness or astigmatism or if the tissue, is too thin to create a firm scar, we recommend Deep Anterior Lamellar Keratoplasty (DALK). With his operation only the diseased cornea is removed in an area of 8mm diameter down to the posterior layers. The latter include Descemet's membrane and the one layered endothelium, both of which must be healthy as is generally the case for those layers up to the latest stage of the keratoconus. The patient's own endothelium is preserved and will stay for his lifetime.
DALK is a permanent procedure that heals Keratoconus.
DALK's in Germany are only performed in very few clinics. The argument for not doing this procedure is that visual acuity match PKP. This in our patients is not the case. The statistic shows that the optical result of DALK is as good as in PKP. Our statistics with high case numbers show identical results of outcomes of both visual acuity and cylinder in DALK vs PKP. (Fig.8)
The success rate for DALK is about 93%. For the success of this operation Descemet's membrane must be bared - freed of all adjacent tissue. This in some instances may not be possible - be it due to overstretching of the tissue by steep cones or by scars - they adhere firmly and cannot be removed. In about 5% the posterior layers open spontaneously so that one has to convert to a penetrating keratoplasty during operation.
A permanent healing cannot be achieved if a penetrating keratoplasty (PKP) was performed because the transplant's lifetime rarely exceeds 10 to 15 years. The additional problem of PKP is the occurence of immune reactions in 6% of the cases. This reaction only occurs in 1% with DALK.