Thermal and mechanical damage of corneal tissue after free-running and Q-switched mid-infrared laser ablation

Flurin Koenz; Martin Frenz; Hans Surya Pratisto; Heinz P. Weber; Holger Lubatschowski; Omid Kermani; Wolfgang Ertmer; Hans Joerg Altermatt; Thomas Schaffner

doi:10.1117/12.168015

1 February 1994 Thermal and mechanical damage of corneal tissue after free-running and Q-switched mid-infrared laser ablation

Flurin Koenz, Martin Frenz, Hans Surya Pratisto, Heinz P. Weber, Holger Lubatschowski, Omid Kermani, Wolfgang Ertmer, Hans Joerg Altermatt, Thomas Schaffner

Author Affiliations +

Proceedings Volume 2077, Laser Interaction with Hard and Soft Tissue; (1994) https://doi.org/10.1117/12.168015
Event: Europto Biomedical Optics '93, 1993, Budapest, Hungary

Abstract

Laser ablation of corneal tissue by mid-infrared laser radiation was studied in dependence of the laser wavelength and the pulse duration. The thermally and mechanically laser induced damage was determined by light microscopy (LM) and scanning electron microscopy (SEM). Fresh porcine eyes were irradiated with three different lasers: Er:YAG ((lambda) equals 2.94 micrometers ), Er:YSGG ((lambda) equals 2.79 micrometers ) and Ho:YAG ((lambda) equals 2.1 micrometers ). The experiments were performed with both, free running (pulse duration (tau) equals 200 microsecond(s) ) and Q-switched pulsed ((tau) equals 100 ns) lasers. The extent of thermally damaged tissue was found to be the same for Er:YAG and Er:YSGG lasers: 8 - 45 micrometers and 2 - 10 micrometers , with the long and the Q-switched pulses, respectively. The Ho:YAG laser induced coagulation zones were 200 - 600 micrometers thick in the free running and 40 - 80 micrometers in the Q-switched mode. The ablation efficiency of Er-lasers was between 4 and 13 times higher than that of the Ho:YAG.

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Flurin Koenz, Martin Frenz, Hans Surya Pratisto, Heinz P. Weber, Holger Lubatschowski, Omid Kermani, Wolfgang Ertmer, Hans Joerg Altermatt, and Thomas Schaffner "Thermal and mechanical damage of corneal tissue after free-running and Q-switched mid-infrared laser ablation", Proc. SPIE 2077, Laser Interaction with Hard and Soft Tissue, (1 February 1994); https://doi.org/10.1117/12.168015

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