Ocular Fundus Auto-fluorescence What Do We See? First In-vitro Investigations
Hammer M., Schweitzer D.
Abteilung experimentelle Ophthalmologie, Augenklinik der Friedrich-Schiller-Universität Jena
Purpose: Alterations in the ocular fundus auto-fluorescence are under discussion to be related to various degenerative retinal diseases, in particular age related macular degeneration. According to recent investigations, this fluorescence may be of diagnostic relevance. However, further knowledge on the chemical substrate of the fluorescence is necessary for appropriate assessment of ocular fundus auto-fluorescence images.
Method: The fluorescence spectra of Lipofuscin, FAD, NADH and advanced glycation end products (AGEs) were recorded by the Jena ophthalmo-spectrometer after excitation at 400 nm, 446 nm, 470 nm, and 510 nm. Fluorescence lifetimes were measured using a scanning laser ophthalmoscope equipped with a pulse laser (pulse width: 100 ps, wavelength: 446 nm), and a module for time correlated single photon counting.
Results: Fluorescence was found for all substances under investigation, however, the fluorescence intensities were strongly dependent of the excitation wavelength. The detected fluorescence spectra showed remarkable overlaps. On the other hand, fluorescence lifetimes were clearly diverse: Lipofuscin: 0.35ns, FAD: 2 ns, AGEs: 0,9 ns and 4.5 ns, and NADH: 0.5 ns and 4.5 ns.
Conclusions: The discrimination of fluorophores expected to be localised at the ocular fundus proved to be difficult by their
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