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.