Analysis by atomic force microscopy of corneal surface roughness after femtosecond laser flap creation and its change with myopic excimer ablation

Session Details

Session Title: LASIK II

Session Date/Time: Tuesday 25/09/2018 | 16:30-18:00

Paper Time: 17:22

Venue: Room A3, Podium 2

First Author: : R.Cañones SPAIN

Co Author(s): :    J. Gros-Otero   S. Ketabi   M. Teus   C. Villa-Collar   S. Casado   M. Garcia-Gonzalez     

Abstract Details

Purpose:

It is well known that the femtosecond laser lamellar cut has some degree of roughness, mostly due to the fact that the laser spots are separated one from another. Nevertheless, as in femtosecond laser assisted LASIK (FS-LASIK), an excimer LASIK ablation is performed, the post-ablation stromal bed should show a marked decrease in roughness. In order to evaluate and to quantify the smoothing effect of excimer ablation, we decided to compare, using atomic force microscopy (AFM), the roughness of the corneal stromal bed, after a Femtosecond lasers device (FS) flap was created with or without an excimer myopic ablation.

Setting:

Clinica Novovisión, Universidad Autónoma de Madrid

Methods:

Using 6 freshly enucleated porcine eyes, we created in every eye a flap using and Intralase® femtosecond laser (Intralase iFS 150 KHz). Additionally in 3 eyes an excimer laser ablation to correct -3 diopters (D) was made, using a WaveLight Allegretto EyeQ 400-Hz (Alcon Laboratories). AFM imaging of the remaining corneal stroma was performed using a JPK NanoWizard II®. Ten different square areas of 20μm x 20μm at the central area of the stroma of each corneal sample were studied. The roughness parameters used was the root-mean-square (RMS) deviation from a perfectly flap plane.

Results:

The RMS deviation were 360 ± 120 nm in femtosecond laser only, and 110 ± 20 nm in those cases where excimer is also involved (p<0.05).

Conclusions:

Our results show that the roughness of the surface treated with excimer is clearly lower than in the group with no excimer ablation, thus the application of laser excimer after a flap creation by femtosecond laser flap creation may soften the nano-irregularities created by this technique, which may cause optical aberrations.

Financial Disclosure:

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