Abstract

SO.21.01

Detection of changes in cellular metabolism caused by retinal vessel occlusion

Dietrich Schweitzer, Sylvio Quick, Martin Hammer, Susanne Jentsch, Jens Dawczynski
Experimentelle Ophthalmologie, Augenklinik, Friedrich-Schiller-Universität, Jena

Background and goal
First pathologic changes occur in metabolism. Thus, alterations in cellular metabolism should be detectable in retinal vessel occlusion.
Method
Changes in the time-resolved auto-fluorescence of endogenous fluorophores e.g. redox pairs FAD-FADH2 or NAD+-NADH will be measured by a home built fluorescence lifetime mapper. The fluorescence is excited by 448 nm laser pulses (80 ps full width at half maximum, 80 MHz repetition rate). The time–resolved auto-fluorescence is detected by time-correlated single photon counting between 490 nm – 560 nm and 560 nm – 700 nm. Measurements were performed in arterial and venous occlusion. The fluorescence decay is 3-exponentially approximated. Images and histograms of lifetimes and amplitudes are available for evaluation.
Results
Best results are demonstrated in arterial branch occlusion. Here, an internal comparison is possible between the fluorescence in supplied and non-supplied regions. Most sensitive is the lifetime tau2 in the short-wave channel, which corresponds to the neural retina. In the supplied region the lifetime is tau 2=560 ps. It increases to tau 2=1160ps in the non-supplied field. This increase is interpretable as rise of protein-bound NADH, which originates in glycolysis.
Conclusion
Changes in energy production from respiratory chain to glycolysis as result of lack of oxygen are detectable by time-resolved fluorescence measurement.

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