A 60 kHz IntraLase femtosecond laser creates a smoother LASIK stromal bed surface compared to a Zyoptix XP mechanical microkeratome in human donor eyes.

PURPOSE To compare the stromal surfaces created by the latest mechanical microkeratome and femtosecond, laser technologies. METHODS Laser in situ keratomileusis (LASIK) flaps were created in six fresh human globes unsuitable for transplantation. The eyes were placed in one of two groups of three globes each. One group had LASIK flaps created with a Zyoptix XP microkeratome using a 120-microm head and a fresh blade for each eye. Another group had flaps created at an attempted 100-microm thickness using the 60 kHz IntraLase femtosecond laser. Immediately following flap creation, the stromal beds were prepared for scanning electron microscopy (SEM). Qualitative roughness of the SEM images was graded by masked observers. Quantitative roughness of the SEM images was assessed using computerized software designed for roughness analysis. Mann-Whitney non-parametric statistical analysis was performed to compare groups. RESULTS A statistically significant difference was noted in bed smoothness as measured by qualitative roughness and quantitative roughness scores. The IntraLase samples showed smoother stromal beds compared to the Zyoptix group (qualitative roughness = 2.0 +/- 0.7 pm vs 3.6 +/- 1.6 pm, P = .03; quantitative roughness = 20238 +/- 1869 pm vs 26368 +/- 8133 pm, P = .03). CONCLUSIONS The 60 kHz IntraLase femtosecond laser and the Zyoptix XP 120-microm head using a new blade produced smooth, good quality, compact stromal beds qualitatively and quantitatively. Because the 60 kHz femtosecond laser permits a tight spot/line separation using low energy, it creates a smoother corneal stromal bed compared to previous femtosecond laser engines.