Characteristics of flaps created with an IntraLase FS60 femtosecond laser versus a Femto LDV femtosecond laser

Objective To compare the features of the laser in situ keratomileusis (LASIK)flaps created with the IntraLase FS60 femtosecond laser versus the Femto LDV femtosecond laser.Methods One hundred and twenty eyes of 60 consecutive patients were enrolled in this prospective study and divided into 2 groups depending on the flap creation method: the lntraLase FS60 group (60 eyes) and the Femto LDV group (60 eyes). The expected flap thickness was 110 μm for both groups. Preoperative all patients were routine inspected and recorded relevant information, including age, diopter, corneal curvature and corneal thickness, etc. Anterior segment optical coherence tomography was used to measure the flap thicknesses of the 5 specified measurements in the 0°,45°, 90° and 135° meridians on the corneas, at one week postoperatively. Independent samples t test and single factor analysis of variance were used for data statistics processing. Results At one week after surgery, the central flap thicknesses were (111.2±3.3)μm and (108.1±3.0)μm, respectively;the whole flap thickness were (110.8±2.3)μm and (109.0±2.2)μm, respectively; the rang of variations were (22.0±6.6)μm and (23.7±5.8)μm, respectively, in the IntraLase FS60 group and Femto LDV group. Both groups were not statistically different (P＞0.05 for all). The average thickness values in the central, paracentral and peripheral zones were not significantly different in the IntraLase FS60 group (F=1.213, P=0.300); while the central zone was significantly thinner than the peripheral zones in the Femto LDV group (F=3.925, P=0.021). In the two groups, the nasal and temporal flap thicknesses were not significantly different and the means of the flap thickness in the four meridians were similar. The maximum deviation from the intended flap thickness (110 μm) was 6.2 μm in the IntraLase FS60 group; while the maximum deviation was 6.7 μm in the Femto LDV group. The difference was less than 5 μm was 57.83% (694/1200) in the IntraLase FS60 group, 53.83% (646/1200)in the Femto LDV group. Conclusion Femtosecond laser flaps are accurate and have good repeatability. The architecture of flaps are uniform and regular. The characteristics of LASIK flaps created with the IntraLase FS60 femtosecond laser versus the Femto LDV femtosecond laser are similar. Key words: Keratomileusis,laser in situ;  Femtosecond laser;  Flap thickness