Abstract
Purpose: :
To asses stromal bed smoothness and cut edge quality in LASIK flaps created with the IntraLase FS150 and the WaveLight FS200 femtosecond lasers and by a mechanical microkeratome.
Methods: :
Sixty freshly enucleated porcine eyes were used for flap creation. Twenty flaps were created with each femtosecond laser microkeratome and 20 with a mechanical microkeratome (SWIND Carriazzo-Pendular). Laser energy and side cut angle were set to be similar in both laser platforms. In each laser group intended flap thickness was set to 100μm for 10 specimens and 120 μm for another 10 specimens. In mechanical microkeratome group 10 specimens had intended flap thickness 110m and 10 specimens 130μm. Flaps were lifted under surgical microscope according to standard LASIK procedure prior to preparation of globes for microscopy. Quality of flap edge and smoothness of bed surface were assessed by means of scanning electron microscopy (SEM) and light microscopy (LM).
Results: :
In SEM images, both lasers demonstrated satisfactory flap quality and smoothness of the stromal bed, with high reproducibility, both for flap thicknesses of 100 μm and 120 μm. In LM images all the laser-treated specimens were characterized by a clean cut; the flaps were geometrically perfect and demonstrated extreme accuracy in maintaining flap thickness. The surface of a stromal bed created with the help of microkeratome demonstrated more prominent irregularities. The most significant morphological difference observed is the occurrence of chatter marks on the edges of the stromal bed, due to the microkeratome blade movement during the flap creation process. The serrations of this kind were typical for both 100 μm and 130 μm flaps. The flap edges also demonstrated similar irregularities, such as chatter marks and serrations.
Conclusions: :
The laser cuts in both laser systems demonstrated satisfying quality in vitro. The femtosecond laser systems performed better in comparison to the microkeratome in terms of flap geometry and surface edge quality.
Keywords: refractive surgery: comparative studies • refractive surgery: LASIK • refractive surgery