Thin-flap LASIK with a High-frequency, Low-energy, Small Spot Femtosecond Laser – Effectiveness and Safety

Objective: To evaluate clinical results of a high-frequency, low-energy, small spot femtosecond laser for the creation of thin corneal flaps in laser in situ keratomileusis (LASIK) used in a comparative case series at a private practice in Brussels, Belgium. Methods: A series of 75 patients selected for LASIK refractive surgery were enrolled for treatment with the Ziemer FEMTO LDV femtosecond laser and received a corneal flap of either 90 μm (59 patients, 103 eyes) or 80 μm (16 patients, 27 eyes) nominal thickness. Prospective evaluation included flap dimensions, intra- and post-operative complications and visual outcomes. Results: Mean flap thickness was 89.03 (standard deviation [SD]: ± 8.26 μm) in the 90 μm group and 81.91 (SD ± 6.80 μm) in the 80 μm group. Mean uncorrected visual was 1.19 ± 0.26 in the 90 μm group and 1.10 ± 0.25 in the 80 μm group. Mean manifest refractive spherical equivalent was –0.12 ± 0.26 D in the 90 μm group and –0.07 ± 0.31 D in the 80 μm group. There was no significant visual loss (≥2 lines loss of best corrected visual acuity) in either group. One flap tear occurred in the 90 μm group (0.97 %) and two pseudo-buttonholes occurred in the 80 μm group (7.41 %). No other clinically relevant complications occurred intra- or post-operatively. Conclusions: The Ziemer LDV femtosecond laser offers a high degree of precision in the creation of 90 and 80 μm flaps for LASIK. Using this device for creating 90 μm flaps can be considered a safe and effective procedure. A higher rate of complications were shown in 80 μm flaps.