In-vitro- und in-vivo-untersuchungen zur presbyopiebehandlung mit femtosekundenlasern

Background. Ultrashort (femtosecond) laser pulses can generate precise cuts in biological tissue without damaging the surface. The application of femtosecond laser technology at the lens was evaluated with respect to a possible treatment of presbyopia. Materials and methods. Femtosecond laser lentotomy was performed on 150 pig lenses in vitro. Cutting geometry and laser settings were optimized to generate smooth cuts with a minimum of produced gas bubbles. Four rabbit lenses were treated afterwards in vivo and were controlled for 3 months post-treatment. The lenses were then extracted and evaluated. Results. With suitable laser settings, light scattering due to residual gas bubbles could be almost completely avoided in pig lenses. A pulse energy of less than 1.2 μJ and a cutting geometry with spot separations of more than 5 μm are important. The rabbit lenses stayed macroscopically clear for 3 months in vivo. Only the cell structures directly adjacent to the laser focus were cut; structures 5-10 μm away appeared to be intact. No cataract formation occurred during this time. Conclusion. Femtosecond laser application allows precise and smooth cuts inside pig and rabbit lenses without damage to adjacent tissue.