Abstract
P 036
Chondroitinase ABC and endo-ß-galactosidase (keratanase) in enzy-matical exposure of the descemet-layer in deep anterior lamellar keratoplasty (DALK)
Sylvia Stadler, Philip Maier, Daniel Böhringer, Thomas Reinhard
Universitäts-Augenklinik Freiburg
Objective
In patients with a healthy endothelium (e.g. keratoconus) deep anterior lamellar keratoplasty (DALK) is an alternative surgical procedure to penetrating keratoplasty, because thereby the anterior layers of the cornea are selectively removed and the endothelium is retained. However, despite the implementation various manual surgical techniques and the usage of the femtosecondlaser complete exposure of the descemet’s membrane (DM) doesn’t succeed in 60% of cases. The aim of our study is to faciliate the exposure of the DM-layer by enzymatical digestion.
Methods
Four partial trephination were performed by the femto-second-laser (diameter: 3mm, depth: 450µm) in each of the cornea samples which were not suitable for transplantation. The 4 originated slots were either filled with 10µl PBS or 10µl enzyme solution (keratanase: 0,1mg/ml or 0,2mg/ml, chondroitinase ABC: 1µmol/ml or 0,5µmol/ml) and incubated by room temperature for 5, 10 or 20 minutes. In half of the slots we tried to remove the remaining stroma using a hockey-knife. Finally all corneas were histologically investigated.
Results
After enzymatical digestion we saw for both enzymes a similar stromal disaggregation. An exposure of the DM-layer via hockey-knife was more frequently achieved after enzymatical digestion than after PBS incubation. However, we observed more ruptures of DM following enzymatical digestion using the hockey-knife than after PBS incubation.
Conclusions
An enzymatical digestion of the residual stroma with chondroitinase ABC and endo-ß-galactosidase after deep lamellar keratektomie leeds histological to a stromal disaggregation. The enzymatically pretreated stroma could be removed a lot easier by a hockey-knife than the untreated stroma. However, this lead to more ruptures of DM. How and when the enzymatical digestion may be useful in DALK will be investigated in further experiments.
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