fs-lentotomie: changing the accommodation amplitude of presbyopic human lenses by fs laser pulses

摘要

According to Helmholtz' theory of accommodation one of the mayor reasons for the development of presbyopia is the increasing sclerosis of the lens. One concept to overcome this hardening of the lens is to regain its flexibility by inducing gliding planes inside the lens. Femtosecond laser pulses are a suitable tool for this treatment. Showing in former work that we could increase the flexibility of enucleated porcine (ex vivo) lenses up to 25 %, we focused our recent work on human autopsy lenses. The age of the human donors ranged between 20 and 70 years. For an evaluation of the gain in flexibility the lens' thickness was measured undertaking the Fisher's spinning test before and after laser treatment. Depending on the age and the quality of applied cutting pattern the lens thickness increased after treatment up to 0.4 mm leading to an theoretical increase of several dioptres of optical power. The flexibility could be increased up to 70 % compared to the measurements before treatment. Since the age of the human donors had a broad range, leading to different degrees of lens hardening, the variance of the measured flexibility changes was up to 30%. An addition the influence of the laser treatment onto the lens on the accommodation amplitude will be shown in a three dimensional finite-element simulation.