Predictability of corneal flap thickness in laser in situ keratomileusis using a 200 kHz femtosecond laser.

PURPOSE: To compare the intended versus the resultant thickness of laser in situ keratomileusis (LASIK) flaps created with a new femtosecond laser and to report the 3-month postoperative refractive outcomes.

SETTING: Wellington Eye Clinic, Dublin, Ireland.

DESIGN: Retrospective consecutive case series.

METHODS: A consecutive series of eyes having LASIK flaps created using a Wavelight FS200 femtosecond laser were included in this analysis. Eyes with preoperative spherical equivalent (SE) myopic refractive errors up to -12.00 diopters (D), hyperopic refractive errors up to +5.50 D, and astigmatism up to 6.00 D received primary LASIK. Outcomes included postoperative flap thickness and 3-month postoperative refraction.

RESULTS: Outcomes in 431 eyes of 258 patients having LASIK with femtosecond flap creation were assessed. With an intended flap thickness of 120 μm, the mean post-LASIK flap thickness was 120.23 μm ± 13.94 (SD). In 349 of 813 eyes, EX500 optical pachymetry measurements were compared with Scheimpflug pachymetry readings. The mean corneal thickness was 553.52 ± 29.81 μm with optical pachymetry and 553.39 ± 29.12 μm with the Pentacam rotating Scheimpflug camera. In 162 eyes, the flap thickness was measured with optical coherence tomography; the mean was 121.94 ± 10.52 μm. Achieved flap dimensions were as intended.

CONCLUSIONS: This study provides evidence of the predictability and lower variability of LASIK flaps created using the femtosecond laser. Consecutive patients having LASIK had good, predictable, and stable outcomes at the 3-month mark.