Photorefractive keratectomy with the erbium: YAG laser |
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Authors: | Michael Mrochen Frank-Peter Meinhard Vladimir Semshichen Richard W. H. Funk Theo Seiler |
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Affiliation: | Augenklinik, Technische Universit?t, Dresden, XX Academy of Science, Scientific Research Center for Technological Lasers, Moskau, XX Institut für Anatomie, Technische Universit?t, Dresden, XX
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Abstract: | BACKGROUND: Ablation experiments and preclinical studies have shown increased thermal damage and surface roughness after photorefractive keratectomy (PRK) with the erbium: YAG laser. MATERIALS AND METHODS: In this study, the thermal damage was investigated on enucleated pig corneas for various laser pulse durations (80 ns to 1 ms) and radiant exposures (0.2-5 J/cm2). The "scanning-spot" method and the fundamental mode photo-ablation were used for spherical corrections. SEM pictures and surface roughness measurements enabled comparison with the morphology after ArF-excimer laser treatment. The surface roughness is one order of magnitude higher compared to the ArF-excimer laser ablation. The surface of the tissue after ablation looks melted. RESULTS: The thermal damage reduces with increased intensity, and at high intensities the thermal damage results in a constant thickness of > 5 microns. CONCLUSIONS: Laser-induced melting processes might be the main reason for the high thermal damage and the increased surface roughness after erbium: YAG laser treatment. This leads to the conclusion that the erbium: YAG laser is not a real alternative to the ArF-excimer laser in PRK. |
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