Marion GIL, PhD

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Light backscattering for early diagnosis and monitoring of corneal stromal pathologies: ex vivo experimental study and modelisation

Marion GIL will defend her PhD Thesis "Light backscattering for early diagnosis and monitoring of corneal stromal pathologies: ex vivo experimental study and modelisation" on Tuesday, May, 21 at 10:30 am at CERIMed laboratory on Campus Timone, Marseille, France.

The Jury will be composed of :
 Christine ANDRAUD, Professeur, Centre de Recherche sur la Conservation, Rapporteur
 Stéphane SERFATY, Professeur, Université de Cergy Pontoise, Rapporteur
 Gaël LATOUR, Maitre de conférences, Université Paris Sud, Examinateur
 Louis HOFFART, Professeur, Aix Marseille Université, Examinateur
 Gaëlle GEORGES, Maitre de conférences, Ecole Centrale Marseille, Co-directrice
 Carole DEUMIE, Professeur, Ecole Centrale Marseille, Directrice de thèse

Abstract : This work presents the experimental and numerical study of angular resolved scattered light by human corneal grafts for the monitoring of pathologies or for early diagnosis.
The cornea is a very particular tissue in the human body due to its transparency property. It is related to low scattering and absorption losses. This low level of scattering, mainly related to a highly particular organized structure of corneal bulk, will increase in pathological cases where the microstructure of the cornea is disturbed. This work focus particularly on the dysfunction of the mechanism that regulates corneal hydration and where edema develops. Changes in corneal bulk occur gradually at different scales of the tissue until a macroscopic change. In this work we propose the study of the angular resolved scattered light, far from the specular direction, for large scattering angles greater than 35 °, in the reflected half-space.
First, we show that this approach allows a greater sensitivity than the analysis of scattered light close to the specular direction used in conventional corneal examination tools. The method grant access to information on corneal bulk changes that is undetectable for other systems.
In a second step, we evaluate the potential of the monitoring of the intensity scattered in different fields of applications. We demonstrate how scattering measurement can detect tissue changes before any corneal thickness increase. Then, we show the interest of this tool to evaluate the efficiency of anti-edematous eye drops or constituents composing it. Next, we will present how this measurement can be used as an additional criterion for sorting corneal grafts in a tissue bank.
Finally, we propose in simulation an early diagnosis method that allows us to determine the rate of corneal bulk disorganization at a scale of ten nanometers. This approach is based on the spectral variation of the scattering. It allows us to consider a new method for diagnosing edema at earliest stages.