Micrometer scale resolution full-field optical coherence tomography (FF-OCT) is developed for imaging human graft corneas. Three-dimensional (3-D) images with ultrahigh resolution (respectively, 1 and 1.5 μm in the axial and transverse directions), comparable to traditional histological sections, are obtained allowing the visualization of the cells and the precise structure of the different layers that compose the tissue. The sensitivity of our device enables imaging the entire thickness of the cornea, even in edematous corneas more than 800 μm thick. Furthermore, we provide tomographic 3-D images of laser incisions inside the tissue at various depths without slicing the studied corneas. The effects of laser ablations can be observed, along various optical sections, directly in the bulk of the sample with high accuracy, providing information on the interface quality and also imaging tiny changes of the tissue structure. FF-OCT appears to be a powerful tool for subcellular imaging of the corneal structure and pathologies on the entire thickness of the tissue as well as interface quality and changes in the collagen structure due to laser incisions on ex vivo human cornea.

In this study, the retention potential and the fouling of ultrafiltration (UF) multichannel hollow fiber membrane regarding nanoparticles (NPs) have been assessed. Filtration experiments of fluorescent 10 nm and 1.5 nm NPs (respectively NP-10 and NP-1.5) suspensions filtered individually were carried out under different transmembrane pressures. A complexification of the feed suspension through the mix of NPs sizes and/or the salinity adding have been investigated. The retention rate (RR), the fouling location and the membrane productivity have been analyzed and compared in each case to determine the influence of salinity and polydispersity of the feed suspensions on NP retention. Results show that RR of NP-10 stays constant when NPs are filtered in ideal suspension (NP-10 / ultrapure water), or when they are filtered with NP-1.5 and/or with 50 mmol L −1 of NaCl and reaches at least 99%. However, RR of NP-1.5 is modified by the presence of NP-10 and/or 50 mmol L −1 of NaCl. This retention rate is considerably decreased by the complexification of suspensions tested. Estimation of NPs quantity blocked at the membrane at the end of the filtration by mass balance showed no significative variation for NP-1.5 (relative to the RR obtained) while a larger quantity of NP-10 remained blocked at the membrane with the adding of NP-1.5 and/or salts in feed suspension. Location of NPs by Confocal Laser Scanning Microscopy (CLSM) at the end of the filtration showed that filtered individually, NP-10 are blocked in membrane skin and on membrane surface while NP-1.5 are blocked in the entire membrane material. Filtered simultaneously, the location of these two sizes of NPs is not modified but NP-1.5 seems to form clusters in the membrane material and the participation of NP-10 and NP-1.5 to the deposit formed on the membrane surface is increased. The adding of salinity leads to the same observations than the filtration of both sizes mixed.

The cornea is the only transparent tissue in the body. The transparency is the main characteristic of the corneal tissue, and depends not only on the transmission coefficient but also on the losses by scattering and absorption. The scattering properties of the cornea tissues become one of the most important parameters in the case of the corneal graft. These scattering properties are studied in this paper in the reflected half area, similar to the diagnosis configuration. We quantify the influence of the cornea thickness and of the epithelial layer on scattering level. The technique of ellipsometry on scattered field is also used to analyze the polarization properties in order to determine the origin of scattering (surface and/or bulk).