Intrastromale refraktive Chirurgie mit ultrakurzen Laserpulsen

Purpose. To investigate the possibilities and techniques for intrastromal ablation of the cornea by the use of ultra-short laser pulses. Method. A laser-induced plasma with a diameter of 8 μm was generated 100-300 p below Bowmans membrane by focussing of a Ti:Saphir laser (λ=805 nm, pulse width: 115 fs,energy: 0.6-3.3 μJ).Scanning the laser beam enabled arbitrary transsections in the corneal stroma.All experiments were performed in porcine eyes 1-4 h post-mortem. Results. Two-dimensional sections were achieved applying a minimal laser energy of 0.6 μJ at a separation of the single laser effects of 10 μm. A 150 pm thick disc was excised 150 pm below Bowmans membrane and extracted through a keratotomy performed by the laser. Sharp-cut edges were observed by slit-lamp biomicroscopy. Conclusions. Ultra-short laser pulses are suitable for precise intrastromal ablation.