Medical Applications of Ultrashort Laser Pulses
The high intensity of focused ultrashort laser pulses enables various medical applications like precise modification and ablation of tissue. Our research focuses on the interaction of femtosecond laser pulses with transparent tissue, especially for applications in ophthalmology.
When ultrashort laser pulses are focused into transparent material, the high intensity within the focal volume leads to nonlinear absorption. The absorbed energy induces a micro plasma, causing the formation of a micro bubble that separates the tissue in a small region of only several micrometers. By the movement of the laser focus, precise cuts can be realized avoiding the need of opening the eyeball [Graefes Arch. Clin. Exp. Ophthalmol. 249, 1567-1573 (2011)].
Non-invasive femtosecond-laser surgery offers great potential for the modification of transparent tissue and is currently discussed as a possible treatment e.g. for presbyopia [Ophthalmologe 113, 1014-1019 (2006)]. Presbyopia, the decreasing ability of the eye to focus at close distance, is mainly caused by the hardening of the crystalline lens with age. Femtosecond laser surgery enables precise cuts within the lens nucleus to soften the tissue. Due to the reduced stiffness, lens flexibility is increased and accommodation can be restored.
Besides the treatment of the lens tissue, fs-laser surgery allows precise opening of the lens capsule (capsulorhexis) to remove clouded lens tissue in case of a cataract. Furthermore, ultrashort laser pulses can be used as a laser scalpel, e.g. to remove a thrombus as a treatment for the apoplectic stroke.