Comparison of Laser In Situ Keratomileusis Flap Morphology and Predictability by WaveLight FS200 Femtosecond Laser and Moria Microkeratome: An Anterior Segment Optical Coherence Tomography Study

To evaluate laser keratomileusis (LASIK) flap thickness predictability and morphology by femtosecond (FS) laser and microkeratome (MK) using anterior segment optical coherence tomography. Fifty-two candidates for the LASIK procedure were stratified into two groups: FS laser-assisted (Allegretto FS-200) and MK flap creation (Moria 2). Flap thickness was determined at five points. The side-cut angle was measured in three directions at the margin interface. LASIK flap assessment was performed one month postoperatively by Spectralis anterior segment optical coherence tomography. Fifty-two patients (93 eyes) were recruited; 49 eyes were stratified to the FS group and 44 eyes to the MK group. The FS group had relatively even flap configurations, and the MK group had meniscus-shaped flaps. Mean differences between planned and actual flap thickness were 12.93 ± 8.89 and 19.91 ± 5.77 μm in the FS and MK groups, respectively. In thin flaps (100 to 110 μm), there was a significant disparity between the two groups (7.80 ± 4.71 and 19.44 ± 4.46 μm in the FS and MK groups, respectively). However, in thicker flaps (130 μm), comparable flap thickness disparity was achieved (18.54 ± 9.52 and 20.83 ± 5.99 μm in the FS and MK groups, respectively). Mean side-cut angle was 74.29 ± 5.79 degrees and 32.34 ± 4.94 degrees in the FS and MK groups, respectively. Comparable flap thickness predictability was achieved in thicker flaps (130 μm), while the FS laser technique yielded a more predictable result in thinner flaps (100 to 110 μm). Different flap morphology was observed in meniscus flaps in MK-LASIK and flap morphology in FS-LASIK.