Purpose:
The diffusion of corrective refractive surgery procedures has increased the scientific interest for the biomechanical behavior of the human cornea. An accurate and reliable biomechanical computational model has been recently proposed by Pandolfi, based on the microscopic structure of the material, the gross geometry of the lens, the mechanical properties of the tissue and the adoption of a constitutive model for soft tissues suitable for the cornea. The present work is an experimental study in which the computational model of Pandolfi, together with other more crude models available in the literature, are validated through the simulation of inflation tests performed on porcine cornea.
Methods:
The experiments, conducted in the BiomechLab of the University of Salerno, consisted in applying a uniform intraocular pressure to a whole cornea, rigidly fixed at its boundary. In keeping with the experimental setup, the displacements of the nodes at the limbus are fully constrained and no rotation are allowed in the models. The internal surface of the cornea is loaded by a uniform IOP, progressively growing from 2 to 40 mmHg. The geometry of the deformed structure of the cornea, at each loading step, was detected through Spectral-domain OCT and reconstructed in 3d with an image reconstruction software. Simulated deformed sections were compared, at several steps of the loading process, with the corresponding sections obtained through image reconstruction of the high resolution images obtained with the portable instrument we adopted (iVue SDOCT).
Results:
The results we get are in good agreement with the predictions of the computer model. In particular the shape of the curvature versus pressure plot predicted by Pandolfi is accurately reproduced by the experiments in the entire range of pressure we consider.
Conclusions:
From our experimental campaign we obtain the indication that the model of Pandolfi is accurate in predicting the deformation of the cornea. The results depend sensibly on the setting of fiber orientation in the model.
Keywords: computational modeling