Viestenz A., Langenbucher A., Hofmann-Rummelt C., Viestenz A., Seitz B.

Department of Ophthalmology, University Erlangen-Nürnberg, Schwabachanlage 6, 91054 Erlangen

Purpose: To evaluate flap dimensions and blade quality with repeated blade use of an automated microkeratome.
Methods: The automated Summit Krumeich-Barraquer Microkeratome® (SKBM, 160 µm plate, intended flap diameter 9 mm, cutting speed up to 20000 osc/min), was utilized to perform a corneal hinged flap in 35 pig cadaver eyes. Seven blades were reused five times each. Flap diameter was measured by planimetry and thickness was assessed by ultrasonic pachymetry. Additionally, scanning electron microscopy (SEM) analysis of single and multiple (up to five times) used blades was performed.
Results: With single use of the blade, mean central flap thickness was 145±25 µm. The vertical / horizontal flap diameter was 9.0±0.03 mm / 8.6±0.03 mm. No correlation was found between central thickness and horizontal (r=-0.15, p=0.4) or vertical flap diameter (r=-0.04, p=0.83). No thickness gradient of the flap was observed in direction from the incision (138±31 µm) to the flap hinge (130±30 µm). If the blade was used more than two times, the flap thickness was smaller at the incision (157±34 µm vs. 124±20 µm; p=0.003) and the hinge (143±24 µm vs. 122±31 µm; p=0.04), but the central flap thickness remained unchanged. The hinge size ranged from 2.5 mm to 6.0 mm (mean: 5.0±0.8 mm). SEM analysis showed a progression of blade irregularities (up to 9.3 mm) and larger tissue remnants on the multiple used blades.
Conclusion: Reproducible flap size of 9 mm diameter and thickness of 145 µm in pig eyes can be obtained with single use of stainless steel blades in the Summit Krumeich-Barraquer Microkeratome®. Because of the peripheral thinning tendency of the flap and the increase of tissue remnants repeated blade use can not be recommended.

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