Hannover 2016 – wissenschaftliches Programm

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SYBO: Symposium Biomedical Optics

SYBO 1: Symposium Biomedical Optics 1

SYBO 1.2: Hauptvortrag

Donnerstag, 3. März 2016, 11:30–12:00, e415

Vortex-beams for precise and gentle dissection in refractive corneal surgery — •Alfred Vogel, Sebastian Freidank, and Norbert Linz — Universität zu Lübeck, Institut für Biomedizinische Optik, Peter-Monnik-Weg 4, 23562 Lübeck

Vortex beams allow for efficient and precise corneal dissection in refractive surgery. Improved precision is important for LASIK, where excimer laser ablation of stromal material corrects the refractive error after the stroma has been exposed by creating and lifting a thin flap as well as for SMILE, where two intrastromal incisions produce a lenticule that is then removed with forceps through small side cuts. For dissection, ultrashort laser pulses are focused in a raster pattern into the corneal stroma and plasma-induced micro-explosions generate cavitation bubbles that cleave the corneal lamellae.

Cutting precision is compromised by the large focus length associated with commonly used IR wavelengths and moderate NAs. The donut-shaped, short focus of vortex beams largely improves the cleavage efficiency along the lamellae, which dramatically reduces the absorbed energy needed for cutting, diminishes bubble formation in the cutting plane as well as mechanical side effects, and leads to a smoother dissection. The new approach is investigated by high-speed photography with 50 Mio frames/s, ex-vivo tissue experiments, and SEM.