New methodology for characterization of corneal mechanical properties: the POPCORN European project

Session Details

Session Title: Corneal Biomechanics

Session Date/Time: Tuesday 13/09/2016 | 16:30-18:00

Paper Time: 16:36

Venue: Auditorium C6

First Author: : M.Ariza-Gracia SPAIN

Co Author(s): :    D. Pinero Llorens   J. Rodriguez Matas   B. Calvo Calzada              

Abstract Details

Purpose:

The aim of this research was the development of an advanced biomechanical numerical modelling for characterizing the mechanical properties of the cornea from the measurements of the corneal deformation induced by an air-puff applied on the cornea.

Setting:

POPCORN European project within the 7th Framework (Grant Agreement 606634). Consortium formed by Alicante Oftalmológica OFTALMAR (Alicante, Spain), Biotronics 3D (UK), Optoelectronica 2001 (Romania), Construzione Strumenti Oftalmici (Italy), UK Intelligent Systems Research Institute (UK) and Aragón Institute of Engineering Research, i3A (Zaragoza, Spain).

Methods:

Data analysis and patient-specific corneal modeling have been performed by means of computational techniques (finite element method and machine learning). In-silico models take into account the non-linear behaviour of the material, large deformations, and the anisotropy due to the preferential orientation of the collagen fibres. In addition, since a measured cornea is naturally deformed, the physiological pre-stress due to the IOP is also incorporated. The simulation of a non-commercial non-contact tonometry test and a predictor of the corneal material have been developed using a set of 130 patients (> 9000 combinations of thickness, CCT, material and intraocular pressure, IOP).

Results:

Results confirmed the influence of CCT, IOP and fibres stiffness on the corneal displacement, being in good agreement with clinical results. Likewise, they confirmed the importance of considering the corneal pre-stress. Our simulations demonstrate the interplay between corneal mechanical response, CCT, IOP and tissue properties. Additionally, collagen fibres located closer to the anterior surface do not contribute to load bearing since the zone is under compressive stress during the air-puff. Diurnal variations in IOP and CCT could influence on the mechanical corneal response, with a variability of the corneal displacement of about a 5%. Finally, the resulting patient-specific material is able to predict the maximum deformation amplitude of an air-jet with an accuracy of less than a 10% (KTC eyes).

Conclusions:

A numerical tool amenable for assessing on the corneal material depending on the mechanical response of the cornea to an air-jet has been developed. Furthermore, it is suitable for being implemented in any commercial device by only providing the input variables: the corneal topography, the intraocular pressure and the corneal maximum deformation amplitude induced by a non-contact tonometer. A precise characterisation of the corneal material will allow assessing the corneal refractive surgeries by taking into account not only the geometry and pressure of the cornea, but also the tissue quality itself.

Financial Disclosure:

NONE