Distribution Of Lenticule Decentration Following Smartsight Using Eye-Tracker Guided Semi-Automated Centration And Registration

To evaluate the performance of auto-centration for corneal lenticule extraction
treatment on a new commercial femtosecond laser system

Victor Derhartunian, MD, 1010 Vienna, Austria
Hamed Haidari, Schwind eye-tech-solutions GmbH, 63801 Kleinostheim,
Germany
Thomas Magnago, Schwind eye-tech-solutions GmbH, 63801 Kleinostheim,
Germany
Maren-Christina Blum, Schwind eye-tech-solutions GmbH, 63801 Kleinostheim,
Germany
Samuel Arba Mosquera, Schwind eye-tech-solutions GmbH, 63801 Kleinostheim,
Germany

Pre- and 3-month post-op tomographies from 48 eyes undergoing lenticule extraction with femtolaser were collected. 
The centre of mass of the central 9-mm of the pre-post-operative differences
has been calculated and considered as an unbiased estimate of the centration. Corneal tomographies (MS-39), as data matrices in
polar/cylindrical coordinates based on constant radial and angular steps, and
treatments performed using a femtosecond laser system
(SCHWIND ATOS).  XY plots for all treatments and two representative metrics split in OD/OS are presented along with statistical summary
for every metric across all treatments and histograms split in X, Y, R.  The differences in
pupil center and limbus center positions have been used as a sanity check.

In the results it was shown, that 80% of the treatments were within 200µm of
decentration. Analysis of the change in the k-reading was reflecting the planned
refractive change and spherical aberration, coma, and higher order RMS revealed
no relevant differences pre- to postop. After three months all eyes were within
±1D of the SEQ and 94% showed an astigmatism of less than ≤0,5D.

Automated centration and cyclotorsion compensation for lenticule creation is an
effective approach to refine the results of myopic astigmatism showing an
excellent centration. Refractive data of SmartSight treatments with cylinder up to
4,25 dioptre showed excellent outcome.