A numerical-experimental protocol to characterize corneal tissue with an application to predict astigmatic keratotomy surgery.

Autor: Ariza-Gracia MÁ; Applied Mechanics and Bioengineering (AMB), Aragón Institute of Engineering Research (i3A), University of Zaragoza, Zaragoza, Spain; Computational Biomechanics (CB), Institute for Surgical Technology and Biomechanics (ISTB), University of Bern, Switzerland. Electronic address: mariza@unizar.es., Ortillés Á; Applied Mechanics and Bioengineering (AMB), Aragón Institute of Engineering Research (i3A), University of Zaragoza, Zaragoza, Spain; Department of Animal Pathology, University of Zaragoza, Zaragoza, Spain. Electronic address: ortilles@unizar.es., Cristóbal JÁ; Applied Mechanics and Bioengineering (AMB), Aragón Institute of Engineering Research (i3A), University of Zaragoza, Zaragoza, Spain; Department of Ophthalmology, University Hospital of Zaragoza, Zaragoza, Spain., Rodríguez Matas JF; LaBS, Department of Chemistry, Materials and Chemical Engineering 'Giulio Natta', Politecnico di Milano, Milano, Italy., Calvo B; Applied Mechanics and Bioengineering (AMB), Aragón Institute of Engineering Research (i3A), University of Zaragoza, Zaragoza, Spain; Centro de Investigación Biomédica en Red: Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Zaragoza, Spain.
Jazyk: angličtina
Zdroj: Journal of the mechanical behavior of biomedical materials [J Mech Behav Biomed Mater] 2017 Oct; Vol. 74, pp. 304-314. Date of Electronic Publication: 2017 Jun 15.
DOI: 10.1016/j.jmbbm.2017.06.017
Abstrakt: Tonometers are intended to determine the intraocular pressure (IOP) and the quality of corneal tissue. In contrast to the physiological state of stress of the cornea, tonometers induce non-physiological bending stress. Recently, the use of a single experiment to calibrate a set of corneal mechanical properties was suggested to be an ill-posed problem. Thus, we propose a numerical-experimental protocol that uses inflation and indentation experiments simultaneously, restricting the optimization space to circumvent the ambiguity of the fitting. For the first time, both corneal behaviors, i.e., biaxial tension (physiological) and bending (non-physiological), are taken into account. The experimental protocol was performed using an animal model (New Zealand rabbit's cornea). The patient-specific geometry and IOP were registered using a MODI topographer (CSO, Italy) and an applanation tonometer, respectively. The mechanical response was evaluated using inflation and indentation experiments. Subsequently, the optimal set of material properties is identified via an inverse finite element method. To validate the methodology, an in vivo incisional refractive surgery (astigmatic keratotomy, AK) is performed on four animals. The optical outcomes showed a good agreement between the real and simulated surgeries, indicating that the protocol can provide a reliable set of mechanical properties that enables further applications and simulations. After a reliable ex vivo database of inflation experiments is built, our protocol could be extended to humans.
(Copyright © 2017 Elsevier Ltd. All rights reserved.)
Databáze: MEDLINE
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