Evaluation of anterior corneal high order aberrations before and after wavefront-optimized femto LASIK for myopia

Session Details

Session Title: LASIK

Session Date/Time: Monday 12/09/2016 | 08:00-10:30

Paper Time: 09:00

Venue: Hall C3

First Author: : M.Arvanitis GREECE

Co Author(s): :    R. Tsopouridou   D. Lioumi   C. Chronopoulou   E. Stathopoulou   V. Liarakos        

Abstract Details

Purpose:

To evaluate coma, trefoil and spherical aberration of anterior corneal surface, before and after WaveFront Optimized (WFO) Femto LASIK, with the use of a Scheimpflug camera and FS200 – EX500 platforms.

Setting:

“Eye Day Clinic”, Private Sector Day Clinic, Athens, Greece

Methods:

We analyzed anterior surface corneal High Order Aberrations (HOA) of 50 eyes, before and one month after WFO myopic Femto Lasik, with the use of FS200 and EX500 platforms (Wavelight, Alcon). Zernike coefficients for spherical aberration (Z0,4), coma (Z±1,3) and trefoil (Z±3,3) were obtained with the use of a Scheimpflug camera (Wavelight Oculyzer II, Alcon), before and one month after Lasik procedure. The coefficients were measured for an estimated corneal diameter of 8mm. Descriptive analysis, Wilcoxon matched pairs test, Spearman correlation and scatter plots were used as appropriate.

Results:

Mean value of coma was 0.36μ (± 0.17) and 0.54μ (± 0.32) pre and post operatively respectively. Post operative coma was significantly higher (p<0.001). Mean value of trefoil was 0.08μ (± 0.06) and 0.11μ (± 0.08) pre and post operatively respectively. Post operative trefoil was significantly higher (p<0.001). Mean value of spherical aberration was 1.21μ (± 0.19) and 1.93μ (± 0.37) pre and post operatively respectively. Post operative spherical aberration was significantly higher (p<0.001) and was significantly correlated with the amount of correction (p<0.001).

Conclusions:

All Zernike terms analyzed, showed changes in magnitude after myopic WFO Femto Lasik. However, regarding coma and trefoil, coefficients remained within normal range, for almost all of the cases. The most significant increase was observed for spherical aberration, probably as a direct result of the change in corneal asphericity, from normal prolate shape to an oblate one. Moreover post operative spherical aberration demonstrated a linear relationship with the attempted refractive correction.

Financial Disclosure:

NONE