[Picosecond infrared laser fiber-assisted sclerostomy (PIRL-FAST) : A first proof of principle analysis].

Introduction. The aim of this study was an analysis of the feasibility of a picosecond infrared laser fiber-assisted sclerostomy (PIRL-FAST) using a novel sapphire fiber and different energy levels of the picosecond laser. Method. The laser-assisted sclerostomy was carried out with a newly generated sapphire fiber of the PIRL-HP2-1064 OPA-3000 (Attodyne, Canada). Immediately after the intervention, the eyes were fixed in phosphate-buffered 3.5% formaldehyde. For subsequent histological analysis the eyes were cut into 4 mu m thick sections and stained with hematoxylin and eosin (H&E, Merck, Darmstadt, Germany). All preparations were then scanned and digitalized using the MIRAX SCAN (Carl Zeiss Microimaging GmbH, Jena, Germany). Results. The pulse energies 150 mu J (N = 4), 175 mu J (N = 6), 200 mu J (N = 7) and 250 mu J (N = 6) were selected. Within the framework of this first feasibility analysis 400 mu m (10 sequential sections) of the sclerotomies were evaluated. The mean area of PIRL-FAST showed a dependency on the pulse energy applied. The diameter of the collateral damage zone (CDZ) depended on the pulse energy used. The largest CDZ could be measured using the highest pulse energy in this experiment (250 mu J). The environmental scanning electron microscope (ESEM) results revealed circular smooth sclerostomy wall with only minimal change of tissue ultrastructure. Conclusion. The PIRL-FAST using sapphire fibers is a new minimally invasive instrument to provide robust stenting from the anterior chamber to the subconjunctival space. Since the PIRL has proven to work efficiently in sectioning several tissues with minimal collateral damage these first proof of principle experiments might pave the way for a new minimally invasive glaucoma surgery strategy. We have already initiated experiments to analyze the wound healing and scar formation in vivo.