Evaluation of Corneal Flap Dimensions and Cut Quality Using the Automated Corneal Shaper Microkeratome

Abstract

To evaluate flap dimensions and cut deterioration with repeated blade use in an automated microkeratome. The Automated Corneal Shaper (Chiron-Adatomed, Munich, Germany), 160-microm plate attached, was used to make a corneal flap in 90 pig cadaver eyes, reusing blades up to five times. Flap diameter was measured by planimetry and thickness was calculated by ultrasound pachymetry. Scanning electron microscopy of stromal beds and blade cutting edges was performed to assess cut deterioration after repeated blade use. Mean flap central thickness was 125 +/- 32 microm. Mean vertical flap diameter was 7.6 +/- 0.4 mm. No correlation was found between thickness and diameter (r = 0.15, P = .45). Progressive thinning of the flap was observed in the direction of the flap hinge. Smooth cuts (using new blades) with periodic chatter lines at the keratectomy edge and in the stromal bed were observed with scanning electron microscopy. Increasing tissue remnants on the stromal bed and decreasing cut quality occurred with repeated blade use. Blades showed larger tissue remnants, nicks, and even folds on the cutting edge proportional to the number of times blades were used. Satisfactory cut quality and reproducibility were obtained after a single use of stainless steel blades in the Automated Corneal Shaper microkeratome. Cut quality was degraded dramatically by repeated use of blades.