COMPARATIVE ANALYSIS OF HIGHER-ORDER ABERRATIONS IN PATIENTS AFTER LASIK WITH FLAP CREATION ON DIFFERENT FEMTOSECOND LASER PLATFORMS

To compare postoperative visual outcomes, refractive stability, and higher-order aberrations (HOAs) in patients who underwent LASIK with flap creation using different femtosecond laser platforms.

The study was conducted at iClinic s.r.o., Ophthalmology Clinic, Bratislava, Slovakia, and iDoctor, Ophthalmology Center, Klagenfurt am Wörthersee, Austria — tertiary centers specializing in refractive and corneal surgery. All procedures were performed by the same experienced surgeon under standardized conditions between January 2024 and October 2025.

This prospective comparative study included 96 eyes of 48 patients who underwent femtosecond LASIK for myopia or myopic astigmatism. Eyes were divided into four groups according to the femtosecond laser platform used for flap creation:

Group 1: Zeiss VisuMax 500,  Group 2: Zeiss VisuMax 800, Group 3: Ziemer FEMTO LDV Z8, Group 4: Ziemer FEMTO LDV Crystal Line. Flap parameters (thickness 110–120 μm, diameter 8.0- 9.0 mm) and excimer ablation profiles were standardized across all groups. Preoperative and postoperative evaluations included uncorrected and best-corrected distance visual acuity (UDVA, CDVA), manifest refraction, corneal topography, and wavefront aberrometry. Higher-order aberrations (coma, spherical aberration, trefoil) were analyzed for a 6.0 mm optical zone at 1 month and 3 months postoperatively using a wavefront sensor and AS-OCT imaging.

All femtosecond laser platforms provided excellent refractive accuracy and visual acuity outcomes, with no statistically significant difference in final UDVA or CDVA at 3 months. However, faster visual recovery and lower HOA induction were observed in the Ziemer FEMTO LDV Z8 group. The mean total HOA increase was lowest in the Z8 group , followed by the Crystal Line  , VisuMax 800  , and VisuMax 500 . Flaps created with Ziemer systems demonstrated smoother stromal interfaces and fewer microfolds on AS-OCT, which correlated with earlier stabilization of visual function.

All femtosecond laser platforms produced excellent and predictable results after LASIK. Differences in pulse energy, repetition rate, and stromal surface smoothness may influence the degree of induced higher-order aberrations and the speed of visual recovery. The Ziemer FEMTO LDV Z8 platform provided the most favorable balance between tissue quality, optical performance, and postoperative rehabilitation speed, making it a highly effective choice for flap creation in refractive surgery.