Effect of New Architecture for Femtosecond Laser Astigmatic Keratotomy on Induced Aberration in Patient-Specific Computational Modeling
Narrative Responses:
Purpose
To compare novel astigmatic keratotomy (AK) incision architectures to standard AK using patient-specific computational modeling to evaluate astigmatic effect and induction of higher order aberration (HOA).
Methods
Finite element modeling was used to perform simulations of femtosecond (FS) laser arcuate corneal relaxing incisions on patient-specific corneal models. Modeling (previously validated clinically) accounted for corneal stroma being denser anteriorly than posteriorly. Simulations of AK incisions of uniform depth and thickness were compared with those of AK incisions whose ends were either deeper, thicker, or both deeper and thicker than the center of the incision. Astigmatic effect and induced higher order aberration were assessed for incisions 30° in length made at the 8mm optical zone.
Results
Compared with incisions of uniform depth and thickness, shallow center incisions achieved 13% greater astigmatic effect, and diminished induced spherical aberration by 26%, coma by 21%, trefoil by 100%, and tetrafoil by 3%. Uniform depth incisions with thicker ends achieved 1% greater astigmatic effect, and diminished induced spherical aberration by 18%, coma by 74%, trefoil by 99%, and increased tetrafoil by 17%. The thicker ends with shallower center incisions achieved 15% greater astigmatic effect, and diminished induced spherical aberration by 20%, coma by 82%, trefoil by 81%, and tetrafoil by 20%.
Conclusion
Novel FS laser AK incisions with thicker ends and shallower center produced optimal results with greatest astigmatic effect and least induction of HOA. All novel architectures generated greater astigmatic effect and less induced HOA than traditional. Control of incision architecture may aid in optimizing vision in FS laser AK