Correlation Of Treatment Decentration With Post-Op Induced Aberrations Following Smile Performed With 2 Mhz Femtolaser Equipped With A Centration Guide

To study the correlation between treatment decentration with post-op induced aberrations following SMILE performed with 2 MHz femtolaser equipped with a centration guide.

Nethradhama Superspeciality eye hospital, Bangalore, India

In this prospective study, SMILE was performed using a 2MHz femtolaser (VisuMax 800), in which the treatment centration is guided by CentraLign software, based on the x and y coordinates of the pupil, measured  at the time of topography acquisition. At the end of the procedure, the machine calculates the treatment decentration based on the degree of offset from the targeted point of centration. The  degree of treatment decentration was correlated using Pearson-correlations with post-op induced aberrations ( measured by ray-tracing, at 4mm pupil size) to study correlation between the two.

Fifty eyes underwent SMILE for myopia of -1 to -10 D SE and astigmatism upto -3D using 120 µ cap thickness and 2 mm superior incision. The mean treatment decentration was 0.14±0.08 mm. The mean pre-op total Higher order aberrations(HOA), Spherical aberrations(SA) and coma aberrations were 0.16 ± 0.15, 0.01±0.04 and 0.08±0.08 µ compared to 0.19±0.12,-0.02±0.04 and 0.13±0.12µ respectively at 3 months post-op. On correlation with treatment decentration the abberations were 0.01, 0.00 and 0.04 respectively, which was not statistically significant ( p-values 0.41,0.91 and 0.17 respectively).All eyes achieved 20/20 or better post-op UDVA without loss of lines of CDVA. No intra-operative complications were noted. 

No significant correlation of treatment decentration with post-op induced aberrations was noted for SMILE performed with faster 2 MHz femtolaser with centration guide, suggesting that the observed treatment decentration may not be significant enough to result in a remarkable induction of higher order aberrations, especially coma.