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O. Stachs, S. Schumacher, M. Hovakimyan, M. Fromm, A. Heisterkamp, H. Lubatschowski, R. Guthoff; Visualization of Fs-laser Pulse Based Micro Incisions Inside Crystalline Lens Tissue. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4383.
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© ARVO (1962-2015); The Authors (2016-present)
Evaluation of a new method for visualization of fs-laser pulse induced micro incisions inside the crystalline lens tissue.
Porcine lens tissue was modified by fs-laser pulses (wavelength 1040 nm, pulse duration 306 fs, pulse energy 1.3-1.6 µJ, repetition rate 100 kHz) in order to create defined planes where the lens fibers are separated. The fs-laser pulses are delivered by a 3D scanning unit and transmitted by focussing optics (NA=0.18) into the lens tissue. The induced micro incisions inside the lens tissue have been examined by using a confocal laser scanning microscope (CLSM) which is based on a user modified Rostock Cornea Module attached to a Heidelberg Retina Tomograph II (Heidelberg Engineering, Germany, wavelength 670 nm). Optical sections were analyzed and have been digitally reconstructed in 3D by using AMIRA (TGS Inc., USA). The scanned volumes were maximum sized with 400x400x100 µm (voxel size 0.78x0.78x0.95 µm).
The spatial arrangement of the lens fiber structure was visualized by ex vivo 3D-CLSM. Lens fibers run parallel to each other with a fiber diameter in-between 3 and 9 µm depending on scanning location. Fs-laser based micro incisions could have been visualized. Depending on pulse energy, spot separation and tissue degeneration (scattering of the tissue) different effects were caused by the applied fs-pulses. Effects like reflecting/scattering properties with intact fiber structures up to definite separated fibers with a wide gap were observed. Too tight overlap and too high pulse energies even caused an incomplete cutting plane due to a highly micro bubble development.
3D-CLSM allows the visualization and analysis of the fs-laser pulse induced micro incisions inside crystalline lens tissue. The visualization without invasive tissue preparation offers a method for studying the outcome of the fs-laser pulse treatment without preparation artefacts. The developed CLSM method may help to optimize fs-laser based procedures in presbyopia treatment.
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