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Updated: Jun 21, 2026
A Workflow to Quantitatively Determine Age-Related Macular Degeneration Lesion-Specific Variations in Fundus Autofluorescence
Published on: May 26, 2023
[Comparison of parameters of time-resolved autofluorescence between healthy subjects and patients suffering from
D Schweitzer1, S Quick, S Schenke
1Bereich Experimentelle Ophthalmologie, Augenklinik der FSU Jena, Deutschland. Dietrich.schweitzer@med.uni-jena.de
Background:
A fluorescence lifetime mapper (FLM) was tested for quantitative estimation of early alterations in age-related macular degeneration (AMD) which are assumed to be in cellular metabolism.
Method:
In FLM time-resolved autofluorescence of the fundus is excited by picosecond (ps) laser impulses at 448 nm and detected in 2 spectral ranges (K1=490-560 nm and K2=560-700 nm) by time-correlated single photon counting. The time-dependent decrease in fluorescence intensity was approximated using 3 decay rates. The calculated lifetimes allow a comparison with endogenous fluorophores of cellular metabolism.
Results:
Initially mean lifetimes were determined for 8 healthy subjects (K1: tau1=118 ps, tau2=584 ps, tau3=2826 ps, K2: tau1=104 ps, tau2=477 ps, tau3=1623 ps). In 15 AMD patients (AREDS categories I and II) the lifetimes were longer (K1: tau1=166 ps, tau2=986 ps, tau3=3309 ps, K2: tau1=137 ps, tau2=583 ps, tau3=1924 ps). The best separation between healthy subjects and patients with early AMD was possible by parameters 1 and 2 in the short-wave channel. Fluorophore-specific alterations in the macula could be demonstrated in isolated cases with advanced AMD.
Conclusion:
Measurements in the 30 degrees fundus field demonstrated that specific alterations were already present even in early AMD and also outside the macula. These act in the neuronal retina, because parameter tau2 is related to this layer. Increases in the lifetime of parameter tau2 in the short wave channel could at least partially be determined by an increase of protein bound NADH, the content of which increases with reduced cellular respiration.
Insights
This study shows that fluorescence lifetime mapping (FLM) can detect early metabolic changes in age-related macular degeneration (AMD). These changes, indicated by longer fluorescence lifetimes, appear even before significant vision loss.
Area of Science:
- Ophthalmology
- Biophotonics
- Cellular Metabolism
Background:
- Age-related macular degeneration (AMD) involves early alterations in cellular metabolism.
- Assessing these metabolic changes is crucial for early AMD detection and management.
Purpose of the Study:
- To evaluate the efficacy of a fluorescence lifetime mapper (FLM) for quantitative estimation of early metabolic alterations in age-related macular degeneration (AMD).
- To correlate fluorescence lifetime changes with cellular metabolism in healthy subjects and early AMD patients.
Main Methods:
- Utilized FLM with picosecond laser impulses (448 nm) and time-correlated single photon counting to measure time-resolved autofluorescence in two spectral ranges (K1: 490-560 nm, K2: 560-700 nm).
- Approximated time-dependent fluorescence intensity decrease using three decay rates to calculate fluorescence lifetimes.
- Compared lifetimes between 8 healthy subjects and 15 AMD patients (AREDS categories I and II).
Main Results:
- Mean lifetimes were longer in early AMD patients compared to healthy subjects.
- Parameters tau1 and tau2 in the short-wave channel (K1) showed the best separation between healthy individuals and early AMD patients.
- Fluorophore-specific alterations were observed in isolated cases of advanced AMD.
Conclusions:
- FLM can detect specific alterations in the neuronal retina, even in early AMD and outside the macula.
- Increased tau2 lifetime in the short-wave channel may indicate increased protein-bound NADH due to reduced cellular respiration.
- FLM shows potential for non-invasive, quantitative assessment of metabolic changes in early AMD.
