title: Simultaneous microstructural and mechanical characterization of human corneas at increasing pressure.
abstract: The cornea, through its shape, is the main contributor to the eye׳s focusing power. Pathological alterations of the cornea strongly affect the eye power. To improve treatments, complex biomechanical models have been developed based on the architecture and mechanical properties of the collagen network in the stroma, the main layer of the cornea. However, direct investigations of the structure of the stroma, as well as its link to the mechanical response, remained limited. We propose here an original set up, associating nonlinear optical imaging and mechanical testing. By using polarization resolved Second Harmonic signals, we simultaneously quantified micrometer (orientation of the collagen lamellae) and nanometer (local disorder within lamellae) scale corneal organization. We showed that the organization of the lamellae changes along the stroma thickness. Then, we measured simultaneously the deformation on the epithelial side of the cornea and the reorientation of the collagen lamellae for increasing intraocular pressure levels, from physiological ones to pathological ones. We showed that the observed deformation is not correlated to initial orientation, but to the reorganization of the lamellae in the stroma. Our results, by providing a direct multi-scale observation, will be useful for the development of more accurate biomechanical models.
authors.affiliation: LMS, École polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau, France.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Benoit
authors.affiliation: LOB, École polytechnique, CNRS, Inserm U1128, Université Paris-Saclay, 91128 Palaiseau cedex, France; IMNC, Univ. Paris-Sud, Univ. Paris-Diderot, CNRS, Université Paris-Saclay, 91405 Orsay cedex, France.
authors.forename: Gaël
authors.initials: G
authors.lastname: Latour
authors.affiliation: LOB, École polytechnique, CNRS, Inserm U1128, Université Paris-Saclay, 91128 Palaiseau cedex, France.
authors.forename: Schanne-Klein
authors.initials: SK
authors.lastname: Marie-Claire
authors.affiliation: LMS, École polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau, France. Electronic address: allain@lms.polytechnique.fr.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Allain
mesh_terms: D003094:Collagen / Q000648:ultrastructure*; D003319:Corneal Stroma / Q000648:ultrastructure*; D006801:Humans; D011312:Pressure
chemical_list: D003094:Collagen
keywords: Biomechanics; Collagen; Cornea; Digital image correlation; Microstructure; Non-linear microscopy