Abstract
Purpose :
A new femtosecond (nFS) laser uses an innovative radial scanning pattern to create a corneal lenticule incision with a key feature of ease-of-removal. At the end of each radial scan, existing sharp turning points with standard high-frequency filter applied introduces high acceleration and jerk for the XY stage motion. In this research, we evaluated a new trajectory smoothing algorithm which replaces all the sharp corners in the trajectory with arc segments. This new algorithm shall reduce the scanning noise and micron-scale system vibration.
Methods :
The nFS surgery system generates a curved dissection surface to make a lenticular incision. The actuator driven XY stage trajectory follows a prescribed profile in state-space that describes the laser scanning system evolution in time. The trajectory incorporates the motion system dynamics and consists of a list of waypoints which are composed of position, velocity, acceleration, and jerk. The corner-free algorithm with Gaussian kernel function embedded is adopted to reduce the sharp corners within the trajectory and make the motion smooth. We compared the acceleration and jerk for the two trajectory smoothing algorithms, i.e., the standard high-frequency-filtering algorithm and the corner-free trajectory smoothing algorithm. For the standard algorithm, the trajectory data were the real motor positions recorded for an nFS system during a preclinical cadaver eye lenticule incision study. For the corner-free algorithm, the trajectory data were modified with the corner-free algorithm for the turning points and otherwise they were the same as the standard case.
Results :
The results are shown in Figure 1 below: in comparison with the standard trajectory smoothing algorithm, the corner-free algorithm reduced the magnitude of acceleration by 56% and reduced the magnitude of jerk by 82%. Further experiment is needed for real lenticule incision trajectories of a test system that uses the corner-free trajectory smoothing algorithm.
Conclusions :
Our research showed that the corner-free trajectory smoothing algorithm can significantly reduce the acceleration and jerk during an nFS system corneal lenticule incision. The same method can apply to corneal flap creation.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.