31 October 2001 Autofluorescence lifetime measurements in images of the human ocular fundus
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Abstract
Measurements of the autofluorescence at the fundus prove to be an important tool in early diagnosis and in discovering the pathomechanism, e.g., in age-related macular degeneration. In addition to the action of lipofuscin in the aging process, flavines play an important role as prosthetic groups. As metabolic changes occur at cellular level, patient-specific optimized therapy should be possible according to endogenous fluorophores, before morphological alterations are manifest. As a first tool for the detection of dynamic autofluorescence, a laser scanner opthalmoscope will be presented permitting lifetime measurements at the living human eye-ground under extremely weak detectable light. Considering histograms of lifetimes after excitation at 457.8 nm and determined at the living human eye ground in parapapillary region, a lifetime (rho) approximately equal to 1.38nm was calculated most frequently in the long-wave emission range ((lambda) $GTR550 nm). This points to the main contribution of lipfuscin. If the emission range is extended down to 515 nm, components with longer lifetimes are additionally detectable. Lifetime measurements at a human fundus specimen confirmed the lifetime of 1.38nm in lipfuscin-rich pigment epithelium, whereas the mean lifetime of an intact fundus was 2.04ns. A comparison of lifetimes before, during, and after breathing 100% oxygen results in a quenching of the mean lifetime of 0.15ns by oxygen.
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Dietrich Schweitzer, Dietrich Schweitzer, Achim Kolb, Achim Kolb, Martin Hammer, Martin Hammer, } "Autofluorescence lifetime measurements in images of the human ocular fundus", Proc. SPIE 4432, Diagnostic Optical Spectroscopy in Biomedicine, (31 October 2001); doi: 10.1117/12.447153; https://doi.org/10.1117/12.447153
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