Wavefront-optimized ablation profiles: theoretical background.
OBJECTIVE
To describe a method for calculating wavefront-optimized ablation profiles to precompensate for the spherical aberration and higher-order astigmatism induced by myopic, hyperopic, and astigmatic corneal laser corrections.


METHODS
IROC-Institut für Refraktive und Ophthalmo-Chirurgie, and Institute for Biomedical Engineering, Swiss Federal Institute of Technology, Zürich, Switzerland.


METHODS
The basic ablation profile for myopic, hyperopic, and astigmatic correction is derived from the 2nd-order Zernike representation of wavefront aberrations. Including 4th-order spherical aberration and higher-order astigmatism in the theoretical calculation of the ablation profile allows precompensation for the expected amount of higher-order aberrations (HOAs). The shapes of wavefront-optimized ablation profiles are compared with the shapes of "classic" ablation profiles for myopic and astigmatic corrections.


RESULTS
The introduction of precompensating spherical aberration and higher-order astigmatism leads to a more aspheric ablation profile with a significant increase in ablation depth (up to 35%) in the midperiphery of the optical zone. The central ablation depth remains unchanged in the myopic correction but increases by 3% in cylinder correction.


CONCLUSIONS
Wavefront-optimized ablation profiles provide a simple method to precompensate for the expected 4th-order spherical aberration and higher-order astigmatism in the average eye. Further clinical studies must be performed to prove the theoretical results; demonstrate the reduction in HOAs; and predict safety, predictability, and stability of wavefront-optimized ablation profiles.
Mrochen
Michael
M
Swiss Federal Institute of Technology and Institute of Biomedical Engineering, University of Zürich, Gloriastrasse 35, CH-8092 Zürich, Switzerland. Michael.mrochen@greenmail.ch
Donitzky
Christof
C
Wüllner
Christian
C
Löffler
Joachim
J
D000465:Algorithms; D001251:Astigmatism / Q000503:physiopathology / Q000601:surgery*; D003315:Cornea / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D006956:Hyperopia / Q000503:physiopathology / Q000601:surgery*; D008962:Models, Theoretical; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D012029:Refraction, Ocular