Mechanical Modelling of Keratoconus

Abstract

Purpose: : in association with a group of researchers in mechanical engineering, the authors describe the conception of a physical model, feigning a cornea, subjected to various pressure and thermal constraints, to understand the genesis and reproduce in laboratory a keratoconus deformation.

Methods: : the created system includes a steel base allowing to fix plastic circular multi-laminated patches, modelling the corneal anatomy, then subjected to thermal and pressure increasing constraints. The stake under pressure is realized by means of compressed air, the system being plunged into a steam room, guaranteeing a thermal homogeneity of the set. The measures made to quantify a deformation or a state of constraint on the models of corneas, uses double refringency materials, in light polarized with use of a bench test of photo-elasticimetry. The optimal results are obtained when the experience is realized under a pressure of 3 bars and in a temperature of 190°c. 3 models will be studied: a model without notch representing a healthy cornea, 2 models with a defect with type of notch (internal face or external face) representing a hurt cornea

Results: : for the model of cornea witness without notch, topographic inhomogeneous modification was not revealed. The study in polarized light showed on the other hand a peak of concentration of constraint at the level of the models presenting notches, deformation close to the keratoconus deformation. The experience seems to show that an initial defect is necessary to end in a final abnormal deformation, comparable to that of a keratoconus when the initial defect is situated in the internal coats of the model.

Conclusions: : the authors tried to model a cornea and conceived a system allowing to feign the appearance of an abnormal deformation of the cornea, similar to that found in keratoconus. This model could help to understand better the pathogenicity of keratoconus

Keywords: keratoconus • cornea: basic science • plasticity