KERATECTOMY DIAMETER AND DEPTH WITH DIFFERENT SUCTION DEVICES USING A MANUALLY GUIDED MICROKERATOME
A. Langenbucher, A.Behrens, B. Seitz, M.M. Kus, N.X. Nguyen, C. Rummelt
Purpose: To determine the accuracy of the lenticle size and the reproducibility of cut depth using four different suction ring sizes provided with a manually guided microkeratome.
Materials and Methods: A flap keratectomy using the microkeratome Model One (Moria, France/Tomey Germany) was performed in a total of 20 freshly enucleated pig eyes, with an intended thickness of 130 pm. The eyes were divided depending on the type of the suction ring (-l, 0, l and 2) in four groups, using one blade without replacing for each group. Macroscopic photography for planimetric analysis of the keratectomy diameter (horizontal and vertical) and ultrasonic pachymetry at three points (initial, center and final blade pass zones) were recorded.
Results: The corneal thickness varied from 870 ± 45 µm in the center, 842± 36 µm in the initial point of keratectomy and 854 ± 46 µm at the end point of the keratectomy. The flap thickness was 120 ± 25 µm, 132 ± 19 µm and 143 ± 27 µm, respectively. The flap thickened progressively with the pass of the microkeratome up to the flap hinge (p=0.001) and with the type of the suction device (p=0.02, ?2-Test). Mean horizontal/vertical flap diameter for suction ring -1 to 2 was 7.76 ± 0.13/8.23 ± 0.14 mm, 7.99 ± 0.15/8.43 ± 0.13 mm, 8.21 ± 0.15/8.61+0.12 mm and 8.74 ± 0.15/8.90-L0.23 mm. A correlation between the flap diameter and the type of suction device was found to be statistically significant (p=0.01, ?2-Test).
Conclusion: The suction ring selected to achieve a certain flap diameter seems to affect the thickness of the flap obtained with a manually guided mikrokeratome. This effect should be under consideration for a proper calculation of lamellar refractive procedures.
Supported by DAAD (grant No. 331 4 04 001, Dr. Behrens)
Department of Ophthalmology, University of Erlangen-Nürnberg, Schwabachanlage 6, D-91054 Erlangen