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Finite element modeling of femtosecond keyhole endokeratophakia surgery

Poster Details

First Author: T.Yap UK

Co Author(s):    H. Studer   K. Pradhan   D. Reinstein   E. Businaro   T. Archer   M. Gobbe     

Abstract Details


To apply a finite element (FE) model to a previously reported endokeratophakia case and evaluate anterior and posterior corneal surface changes.


Tilganga Institute of Ophthalmology, Kathmandu, Nepal. Integrated Scientific Services, Biel, Switzerland.


Pentacam front and back corneal surface elevation data were used to warp a spherical template corneal FE model to create a patient-specific FE mesh, with the initial stress distribution computed using an iterative approach. The FE model included non-linear elastic characteristics of the stroma. The endokeratophakia procedure was recreated; a donor lenticule (-10.50D, 5.75-mm zone, 127-μm thick) was inserted into a lamellar pocket (180-μm deep, 6.25-mm diameter), and two 2-mm small incisions at 150˚ and 330˚. Anterior and posterior surfaces, computed by the FE model, were compared to clinical data to assess accuracy and reliability of FE modeling.


The postoperative axial curvature produced by the model closely resembled the patient data; average curvature was 48.01D clinically and 48.23D in the simulation, corneal astigmatism was 3.01D clinically and 2.88D in the simulation. The posterior best-fit sphere elevation map also matched the patient data, replicating inward bulging of the posterior surface by about 50-μm. Stress distribution modeling predicted a stress increase by 159.94±73% in the cap, and a stress decrease by 32.41±21% in the stromal bed.


FE modeling of the cornea reproduced the clinically observed anterior and posterior corneal surface changes following an endokeratophakia procedure. This case sets the stage for further study to refine and yield predictive FE modeling for the evaluation of corneal refractive surgical procedures.

Financial Disclosure:

One or more of the authors has significant investment interest in a company producing, developing or supplying product or procedure presented, One or more 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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