Abstract
Purpose :
Several groups have tested the impact of seasonal variations in human eyes undergoing refractive surgery, reporting different influence on post-operative outcomes. However, clinical results can be largely influenced by the calibration routine of the lasers, which may or may not get affected by seasonal variations in a similar manner. We retrospective analyzed the effect of seasonal changes in PMMA and PET ablation Performance using large series of commercial excimer laser systems.
Methods :
826 consecutive SCHWIND AMARIS systems (including models 500E, 750S, 1050RS) manufactured from February 2012 to February 2018 (6 years) were retrospectively reviewed. For every system, PET and PMMA ablations were considered. All ablations were conducted in climate controlled environment at the SCHWIND production facility in Kleinostheim, Germany. The lasers were stratified depending on the season of the year and month of the year. Single laser pulse fluence, nominal number of laser pulses, mean performance, standard deviation, and technical performance of the system (comprising distribution of the two energy settings) were analyzed. Student’s T-test was used to compare stratified values with global averages for the statistical analysis. Percentage deviation in stratified values of each parameters was calculated with respect to the global averages.
Results :
The seasons winter and summer showed statistical significant variations with respect to the global values for all tested parameters except nominal number of laser pulses for high and low fluence setting. The metric technical performance of the analyzed systems showed a stronger PMMA ablation performance in summer time compared to a weaker performance in winter time, with maximum seasonal deviation of 6%. The results were consistently confirmed in seasonal as well as monthly analyses.
Conclusions :
This large scale retrospective cross sectional study demonstrated a cyclic winter-summer variation in PMMA ablation using the SCHWIND AMARIS lasers. Comparing these results with clinical findings, showing a weaker performance in summertime, and stronger performance in wintertime, our analysis showed an opposite trend in performance on PMMA.
This is a 2020 ARVO Annual Meeting abstract.