97th DOG Annual Meeting 1999
P55
EXPERIMENTAL EVALUATION OF TWO LAST-GENERATION AUTOMATED MICROKERATOMES: HANSATOME® AND SUPRATOME®
A. Langenbucher, A. Behrens, M. M. Kus, C. Rummelt, B. Seitz
To compare flap dimensions, cut quality and blade deterioration after its reuse in an experimental setting using two last-generation microkeratomes.
Methods: Two pivoting-head principle microkeratomes, the Hansatome® and the Supratome®, were used to perform a corneal flap in 50 freshly enucleated pig cadaver eyes, with an intended thickness of 160 µm. Provided stainless steel blades were used from one to five times. Flap diameter was measured by planimetry and thickness calculated using ultrasonic pachymetry at three different locations. Scanning electron microscopy (SEM) of stromal beds and blades' cutting edges were performed to assess the cut and blade deterioration after repeated use.
Results: Mean flap central thickness (Hansatome®/Supratome®) was 151±18 µm / 192±32 µm. Progressive thinning/thickening of the flap was observed in direction towards the hinge (P=0.003/P=0.021). Mean vertical flap diameters of 8.9±0.3 mm / 8.0±0.4 mm, differed significantly (P=0.001). No correlation was found between thickness and diameter (R=0.03; P=0.935 / R=0.12; P=0.603). At SEM, smooth cuts were observed with both keratomes using a new blade. Periodical chatter lines at keratectomy edge were present, and were more pronounced after blade reuse. Cut quality, blade deterioration and small tissue remnants on the blade surface were noted with repeated blade use, especially using the Supratome®.
Conclusions: Local flap thickness and flap diameter variations are inherent to the instrument used. Comparable cut surface quality can be obtained with new blades. Although cut and blade deterioration appears to be minor after two reuses, the presence of tissue remnants on the blade surface still limits its reuse.
Department of Ophthalmology, University of Erlangen-Nürnberg, Schwabachanlage 6, D - 91054 Erlangen, Germany
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