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R. Khoramnia, C. Winkler von Mohrenfels, G. Hoelzlwimmer, L. Quintanilla-Martinez, C. Donitzky, C. Wuellner, C. P. Lohmann; Effect of Three Different Excimer Laser Ablation Frequencies (200 Hz, 500 Hz, 1000 Hz) on the Cornea Using WaveLight Concept System 1000. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2443.
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New excimer lasers with higher repetition rates are developed in order to reduce the treatment time, to avoid drying of the cornea during treatment and to make the ablation more convenient for the patient. The aim of this experimental study was to investigate potential side effects on human and porcine cadaver eyes that might be induced by excimer laser ablation with different ablation frequencies (200, 500 and 1000 Hz).Setting: Augenklinik, Klinikum rechts der Isar, Technische Universitaet Muenchen, Munich, Germany.
For this study, fresh porcine eyes were obtained from the butcher and human donor eyes, not suitable for transplantation, were obtained from the eye bank. After central epithelial abrasion, a - 9 D photoablation was performed on all eyes with different ablation frequencies (200, 500 and 1000 Hz; three eyes per group) using WaveLight Concept System 1000. Three eyes with central abrasion were used as a control group. The surface of the stroma as well as the structure and ultrastructure of the corneal cells and stroma were evaluated thoroughly using light microscopy (PAS and Picrosirius red staining), transmission electron microscopy (TEM), and scanning laser electron microscopy (SEM).
Light microscopy was performed on all samples. The distribution of collagen fibers and keratocytes was comparable in all different ablation frequencies. Also, the ultrastructural evaluation of keratocytes and fibers, assessed with transmission electron microscopy, was equal in all three different ablation frequencies. Scanning laser electron microscopy revealed in all ablation frequencies a smooth surface with no difference between the three ablation rates.
The structural and ultrastructural evaluation of the different ablation frequencies (200, 500, 1000 Hz) showed no specific side effects that could be associated with such high repetition rates. The quality of the ablation was comparable in all three different laser ablation frequencies. 1000 Hz excimer laser can provide the same ablation quality as slower platforms, however, offering the advantage of requiring less treatment time than the other examined laser platforms with lower repetition rates. Therefore the WaveLight Concept System 1000 with a repetition rate of 1000 Hz seems to be a promising new device in refractive surgery.
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