Faithin Omaha eBook Collection

Download or read book In Vivo Two-photon Ophthalmoscopy written by Robin Sharma and published by . This book was released on 2015 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Light-sensitive molecules such as rhodopsin present in photoreceptors are responsible for detecting light and subsequently initiating multi-step biochemical cascades, namely phototransduction and the visual cycle. Many retinal diseases are known to be caused by a breakdown of these cascades, making them prime targets for ongoing vision restoration efforts although it has been notoriously difficult to observe their activity during light and dark in the living eye. Additionally, on its way to the photoreceptors, light has to propagate through the neurons responsible for transmitting this information to the brain. These cells are naturally translucent and although they are implicated in many diseases, current imaging techniques have been unable to image these retinal layers at a cellular scale. The neural circuitry in the retina that allows us to see is complicated, spanning across several cellular layers. Most of what we know about retinal circuitry is from electrophysiology but newer methods need to be developed to accurately measure neuronal responses in the intact, living eye with minimal visual stimulation. The goal of this work is to see the cells that allow us to see, and to develop a way to track the activity of the retina at a cellular scale in the living eye. All cells in the retina contain endogenously fluorescent molecules that are natural markers for cell health and physiology but their fluorescence cannot be accessed through conventional imaging methods because their excitation spectra lie in the ultraviolet regime outside the spectral transmission window. To target these molecules in the living eye, we have developed adaptive optics assisted two-photon fluorescence ophthalmoscopy for mouse and monkey animal models. Initially, the feasibility of tracking retinal function with this method was demonstrated with exogenous fluorophores that are sensitive to changes in intracellular calcium concentration. Next, these were deployed in the unlabeled retina to indirectly track the regeneration of rhodopsin in photoreceptors by monitoring autofluorescence from molecules involved in the visual cycle. Also, by utilizing the intrinsic contrast offered by endogenous fluorophores, two-photon imaging has also enabled visualization of various retinal structures that are otherwise invisible. With advancement of this technology, it could be used for accelerating vision restoration methods and clinical diagnostics."--Pages viii-ix.