Fs-laser induced elasticity changes to improve presbyopic lens accommodation

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 delay the process of sclerosis or even regain the deformation ability, of the lens might be the treatment of the lens by femtosecond laser pulses. Our aim was to evaluate appropriate laser parameters for this possible treatment and to analyse potential changes in deformation ability of the treated lenses. We performed different cutting patterns in enucleated pig lenses (ex vivo) using the disruptive effect of an ultrafast near-infrared laser induced optical breakdown. Pulse energies and spot separation of the laser pulses were varied to investigate the effect on the generated cut. For an evaluation of the gain in deformation ability the lenses were rotated before and after treatment and the changes in lens thickness due to centrifugal forces were measured. In result. a smooth cutting was possible with appropriate parameters. The experiments showed an increase of elasticity in 70% of the eyes. When the lenses were treated more statistically. An average deformation ability increase of nearly 20%, determined by the change of thickness between untreated and treated lens, was measured.