Effect of 60 kHz and 150 kHz Femtosecond Lasers on Corneal Stromal Bed Surfaces: A Comparative Study

Purpose. To compare the effect of 60 kHz and 150 kHz femtosecond (FS) laser on the corneal stromal bed surfaces (SBS). Methods. Sixteen human donor corneal tissues unsuitable for transplantation were used. Anterior and posterior lamella was obtained using 60 kHz and 150 kHz FS laser. A standard depth of 400  μ m was set for anterior lamellar keratoplasty (ALK) and endothelial lamellar keratoplasty (ELK). The quality and smoothness of the SBS post-FS laser dissection were graded for statistics. Results. No intraoperative complications were found. The side cuts were straight, and the SBS appeared smoother in cuts obtained using 150 kHz. The average values of the SBS quality of the anterior lamellar cut were found to be 2.25 (±0.28) for 60 kHz and 3.125 (±0.25) for 150 kHz (P = 0.0039). Whereas, 2 (±0.4) for 60 kHz and 2.75 (±0.28) for 150 kHz (P = 0.0273) was the quality observed in endothelial cuts. No significant difference was found between anterior and posterior cuts performed using the same FS laser (60 kHz or 150 kHz) (P > 0.05). Conclusions. The 60 kHz and 150 kHz FS lasers are equally effective in performing lamellar dissection for ALK and ELK. 150 kHz FS laser allows a tighter spot and layer separation which creates a slightly smoother SBS.