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En route to improved early detection of neurodegenerative diseases. Non-invasive examination of retinal metabolism by analyzing fluorescence lifetime and anisotropy of cellular redox states.

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Project description

Auto- fluorescence imaging of the ocular fundus is an emerging technique in routine ophthalmic diagnostics. It reveals important details on pathologic alterations of the retinal morphology. Great advances in the treatment of diseases such as diabetic retinopathy and age related macular degeneration (AMD), however, could be made if performed before morphological alterations are present. This needs diagnostic capabilities based on functional imaging techniques such as fluorescence lifetime imaging ophthalmoscopy (FLIO).This technique, developed in our lab, has the potential to investigate very early alterations in the cellular energy metabolism by the observation of the redox state using NADH or FAD fluorescence as well as the detection of metabolic by-products. First clinical trials revealed a good discrimination of diabetic patients, AMD-patients, and controls. More information, however, is needed regarding the pathologic alteration of the intrinsic fluorescence of the retina and retinal pigment epithelium (RPE).
Goal of the proposed project, therefore, is the non-invasive optical investigation of the energy metabolism in retinal degeneration. This shall be done by the measurement of fluorescence spectra, fluorescence lifetimes, and fluorescence anisotropy of NADH and FAD in cell- as well as organ culture models of retinal degeneration. This will be induced by pathognomonic conditions, such as hypoxia, hyper-glycaemia, and photo-oxidative stress, in the cultures. This project intends to investigate the influence of the mentioned stress conditions on the concentration of free as well as protein bound NADH and FAD. New recording techniques as well as new models and algorithms for the analysis of fluorescence data will be developed and applied to the models of retinal degeneration mentioned above.

Two-photon (760 nm) excited fluorescence lifetimes (emission at 500-550 nm - left column - and 550-700 nm – right) of retinal structures: nerve fibers (a, b), ganglion cells (c, d), inner nuclear layer (e, f), outer nuclear layer (g, h), photoreceptors (I, j), and RPE (k, l).

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