8 October 2003 Evaluation of time-resolved autofluorescence images of the ocular fundus
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Abstract
Changes in the metabolism can be assumed as a first sign of several ocular diseases. If such metabolic alterations are detectable, diseases might be treatable, before morphological alterations are manifest. The redox pairs of co-enzymes fluoresce after excitation and change their fluorescence properties depending on the oxidative state of cellular metabolism. Metabolic by-products and connective tissue exhibit also auto-fluorescence. The detection and discrimination of endogenous fluorophores at the fundus by selected excitation or evaluation of emission spectra is not possible with a high spatial resolution. The lifetime of electrons in the excited stage is also substance specific and is not influenced by the absorption spectra of non-fluorescent substances at the fundus. For that reason, a Laser Scanning Ophthalmoscope was developed for the 2-dimensional measurement of time - resolved auto-fluorescence at the living human eye-ground. In first studies, different changes in auto-fluorescence were found after respiration of oxygen between fundus sites. Between young and older persons as well as patients suffering from age-related macular degeneration different lifetime-ranges were detected from the same anatomical region. For comparison, lifetime measurements were performed on single substances. In a first step of interpretation, the frequency distribution of each lifetime in a region of interest can be compared between in vivo and in vitro measurements. Presenting the results in Tau 1-Tau 2 diagrams, specific clusters can be found in both types of measurement, covering each other partially and allowing interpretation of measurements from the living human eye.
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Dietrich Schweitzer, Dietrich Schweitzer, Martin Hammer, Martin Hammer, Frank Schweitzer, Frank Schweitzer, Stefan Schenke, Stefan Schenke, Elizabeth R Gaillard, Elizabeth R Gaillard, } "Evaluation of time-resolved autofluorescence images of the ocular fundus", Proc. SPIE 5141, Diagnostic Optical Spectroscopy in Biomedicine II, (8 October 2003); doi: 10.1117/12.499641; https://doi.org/10.1117/12.499641
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