Multiphoton-mediated corneal flap generation using the 80 MHz nanojoule femtosecond near-infrared laser

PURPOSE: To evaluate whether corneal flaps can be generated by the 80 MHz near-infrared, intense nanojoule femtosecond laser based on multiphoton absorption. METHODS: A solid-state Ti:Sapphire femtosecond laser system was integrated in an inverted JenLab Femt-O-Cut laser scanning microscope. A diffraction-limited 40X objective was used to induce multiphoton ionization and plasma production, New Zealand albino rabbits and porcine eyes were used. Surgical outcomes were determined using frame and line scans with nanojoule pulses at a wavelength of 800 nm. RESULTS: Surgical performance was assessed by optical imaging, histology, and electron microscopy. No significant corneal turbidity was observed. Optical imaging and histological examinations detected virtually no perturbation in the surrounding tissue. Corneal flaps and stromal lenticules were generated. Wound repair of the unlifted flaps was observed up to 90 days postoperatively. CONCLUSIONS: Surgical results and follow-up studies confirm that this femtosecond laser at nanojoule pulse energy is able to generate corneal flaps precisely, without causing visible collateral damage to the surrounding tissue or overlying epithelium.