Characterization of human corneal grafts’ transparency by optical coherence tomography and scattering measurements

Abstract

AbstractPurpose In clinical and graft sorting applications, cornea’s transparency is only subjectively qualified. The aim of this study is to bring tools to achieve transparency quantification regarding the evolution of edema within the tissue.Methods The samples are human corneal grafts rejected from bank of tissue due to physiologic issues, which are submitted to swelling protocol to study their properties with edema. A multiscale analysis of the microstructure imaged by 1 µm resolved Optical Coherence Tomography (OCT) combined with a detailed characterization of backscattering properties is performed. Electromagnetical modelization is used to numerically link scattering measurements with structural defects observed with OCT.Results Backscattered intensity measurements enable corneal grafts’ transparency evaluation (backscattering level increases with swelling). Moreover, microstructural tissue modifications occurring during swelling (microstructure disorganization and heterogeneities) are highlighted by OCT imagery. We show that the observed heterogeneities imply higher scattering levels and explain the experimental results.Conclusion Combining both techniques allows linking the scattering behavior with the evolution of microstructures within the tissue and permits to quantify corneal grafts transparency. This study has to be extended to tissues eligible for graft but this characterization in the backscattered space could directly be applied to future study of tissues before removal or to in vivo diagnosis.