Predictability of Corneal Flap Thickness in LASIK Using the WaveLight FS200 Femtosecond Laser

250 of 250 words) Purpose: To compare the intended versus resultant thickness of laser in situ keratomileusis (LASIK) flaps created with a new femtosecond laser (WaveLight FS200 Femtosecond Laser, WaveLight GmbH, Alcon Laboratories) and to report refractive outcomes at 3 months posttreatment. Setting: Wellington Eye Clinic, Dublin, Ireland Design: Retrospective consecutive case series Methods: A consecutive series of eyes having LASIK flaps created using the 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 +5.50D, and astigmatism up to 6.00D received primary LASIK surgery. Outcomes assessed included post-treatment flap thickness and 3 month post-treatment refractive outcomes. Results: Outcomes of 431 eyes of 258 patients with LASIK flaps made using the same femtosecond laser were assessed. With an intended flap thickness of 120 microns (μm), the average post-LASIK flap thickness ± standard deviation achieved was 120.23 ± 13.94 μm. In 349 of the 813 eyes, the EX500 optical pachymetry measurements were compared to Scheimpflug pachymetry readings. The mean corneal thickness was 553.52 ± 29.81μm with EX500 pachymetry and 553.39 ± 29.12 μm with Pentacam. In 162 eyes flap thickness was measured with OCT and found to be 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 WaveLight FS200 Femtosecond Laser. Consecutive patients undergoing LASIK were found to have good, predictable, and stable outcomes at the 3 month mark. LASIK Flap Predictability Word count: 3814 3