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Laser Bridge AK, a novel incision architecture for femtosecond laser astigmatic keratotomy: comparison and validation of patient-specific computational modeling

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Session Details

Session Title: LASIK II

Session Date/Time: Tuesday 08/09/2015 | 14:00-16:00

Paper Time: 15:21

Venue: Room 10

First Author: : A.Nevyas-Wallace USA

Co Author(s): :    C. Roberts, PhD   H. Studer, PhD                 

Abstract Details


To build and to validate a patient-specific computational model of a novel astigmatic keratotomy (AK) incision architecture, the Laser Bridge AK. In order to mitigate the tendency of AKs to be overcorrected in the center and undercorrected at the ends, this incision is shallower at its center than at the ends. In addition, a second purpose was to compare outcome predictions between Laser Bridge AK and uniform AK.


Surgery and clinical examinations performed in private practice with ambulatory surgical center; computational modeling developed by Integrated Scientific Services-AG,Nevyas Eye Associates, in Bala Cynwyd, Pennsylvania, USA.


A 76-year-old man underwent phaco/IOL with 9mm optical-zone nasal AK, 150 microns shallower centrally than at ends, using DuoTrak blade. Incision morphology was measured using Optical Coherence Tomography and Slit-Lamp Photography. Laser Bridge AK's novel architecture was simulated using finite element modeling; this custom mathematical function considered corneal incompressibility, nonlinearity, fiber-induced anisotropy, and inhomogeneity. Pre-operative patient-specific Galilei tomography was imported into Optimeyes software. The simulated incisions' result was calculated with ABAQUS. Post-operative results were compared to the simulated post-operative model for validation. The validated model was then used to compare outcome predictions between Laser Bridge AK and uniform AK.


The patient's astigmatism on refraction was reduced from 1.75D against the rule to 0.25D with the rule. The simulated outcome was compared with the postoperative Galilei corneal tomography. The simulated outcome showed a close match to the measured post-operative results. Compared with the model's predicted outcome for a traditional AK of uniform depth and thickness, the Laser Bridge AK was predicted to have substantially less induced higher order aberrations, as well as greater astigmatic effect.


Patient-specific finite element modeling of the Laser Bridge AK was validated for the patient modeled. Our novel incision architecture for femtosecond laser AK – Laser Bridge AK Incisions with shallower center – produced optimal simulation results with greater correction of astigmatism, yet substantially less induction of HOA than traditional incision architecture. Our ability to control incision architecture could potentially allow the femtosecond laser to improve both uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA). Future studies include comparing different novel incision architectures.

Financial Interest:

One of the authors is employed by a for-profit company with an interest in the subject of the presentation, One of the authors receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented

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