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Full-Field Optical Coherence Tomography (FF-OCT) reveals submicrometric morphological details in retinal explants without the use of contrast agents. Dynamic FF-OCT (D-FF-OCT) takes advantage of the temporal evolution of the local FF-OCT signal to reveal a movement-dependent contrast inside tissues, mostly relying on cellular motility. Compared to regular FF-OCT images, the relative contrast from stationary structures such as nerve fibers is reduced, and contrast inside cells is enhanced, revealing many more cells, as well as the position of nuclei, and cell metabolism.
We used a multimodal FF-OCT, D-FF-OCT and fluorescence microscope to compare and identify the structures observed in D-FF-OCT, which allowed us to reconstruct the full 3-D micrometric organization of corneal and retinal explants. In healthy explants, this multimodal association allows the label-free specific detection of all cell populations, except from the Mueller cells, and of several structural features such as nerve and collagen fibers, and pedicles and spherules. D-FF-OCT also accesses several functional contrasts (relying on metabolism, mechanical and electrical activity) that can be combined to monitor the tissue health over time.
It is anticipated that such a combination of static and dynamic OCT information may be used in vivo in future for the early detection of ocular pathologies. To this end, we tried here to foster our understanding of the progression and occurrence of such diseases in animal models. We notably used this optical system to follow the evolution of stem cells injected in the cornea and to assess the concentration of macrophages in retinas with inflammation.
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