Reproducibility of laser in situ keratomileusis flap thickness using a new multifunctional femtosecond laser platform and correlation with clinical preoperative measurements.

Purpose: To analyze the reproducibility of laser in situ keratomileusis (LASIK) flap thickness (target 120 μm) using the multifunctional femtosecond laser (Lensx) and correlate postsurgical measurements with preoperative factors.

Setting: Hospital Oftalmológico Visão Laser, Santos, São Paulo, Brazil.

Design: Prospective case series.

Methods: Patients with stable refraction for over a year were evaluated. Patients who submitted to refractive surgery with -1.25 to -6.00 diopters (D), with or without astigmatism up to -4.00 D, and corneal curvature of 40.00 to 47.00 D were included. At 100 days postoperatively, an independent examiner performed 4 high-resolution tomographic sections of the cornea for each eye at 45- to 225-degree, 90- to 270-degree, 135- to 315-degree, and 0- to 180-degree meridians. Two masked experienced observers analyzed each section using measuring points located at the center of the cornea (0.0 mm), 2.0 mm to the left and to the right of the center, and 4.0 mm to the left and to the right of the center.

Results: The study comprised 33 patients (63 eyes), aged 21 to 50 years. A significant difference from the target flap thickness (120 μm) was found in 2 of 20 measurements; however, the actual difference was approximately 2.2 μm. Interrater reliability was excellent (ICC > 0.75), with an interrater bias close to 0. Clinical measurements were not predictive of the set of 20 postoperative measurements.

Conclusion: Reproducibility of the multifunctional femtosecond laser was good for LASIK flap creation and no predictive correlation was found with preoperative clinical factors.