Purpose: Laser-assisted in situ keratomileusis (LASIK) requires precise corneal flap cutting. Especially the creation of thin flaps has recently gained importance for thin-flap LASIK. Currently, there is a trend towards faster femtosecond lasers that can produce flaps in a short period of time. We analyzed flaps created with a 200-kHz femtosecond laser concerning their cut precision, morphology, and histology.
Methods: Femtosecond laser flap cutting was performed on 36 porcine cadaver eyes using the prototype 200-kHz femtosecond laser UltraFlap (WaveLight GmbH, Erlangen, Germany). The eyes were assigned to 3 thickness groups, with a cut depth of 100 µm, 130 µm, or 180 µm, respectively. Additionally, flap diameters were varied, ranging from 8.0 mm to 9.5 mm. Flap thicknesses were determined with a micrometer gauge. Flap diameters were measured with a sliding caliper. Furthermore, flaps were created for histologic examination.
Results: There were no complications during flap creation. The mean flap thickness and standard deviation was (in micrometers) 96.33 ± 7.45 (intended thickness: 100), 134.67 ± 4.96 (intended thickness: 130), and 174.59 ± 9.35 (intended thickness: 180), respectively. The flap diameter revealed a mean (in mm) of 8.03 ± 0.15 (intended diameter: 8.0), 8.56 ± 0.10 (intended diameter: 8.5), 9.09 ± 0.10 (intended diameter: 9.0), and 9.54 ± 0.15 (intended diameter: 9.5), respectively. Histologic examination showed very little to almost no changes in the structure of the corneal stroma.
Conclusions: Flap creation could be performed easily without any complications. The morphology and accuracy of the cuts were very reliable and precise. Histology showed a smooth cut.