Purpose: Fluorescence lifetime imaging ophthalmoscopy (FLIO) provides in vivo metabolic mapping of the ocular
fundus. Changes in FLIO have been found in e.g. diabetes patients. The influence of short term metabolic changes
caused by blood glucose level changes on is unknown. Aim of this work is the detection of short-term changes in
fundus autofluorescence lifetime during an oral glucose tolerance test.
Methods: FLIO was performed in 10 healthy volunteers (29±4 years, fasting for 12h) using a scanning laser
ophthalmoscope (30° fundus, 34μm resolution, excitation with 473nm diode laser with 70 ps pulses at 80 MHz
repetition rate, detection in two spectral channels 500-560nm (ch1) and 560-720nm (ch2) using the timecorrelated
single photon counting method). The blood glucose level (BGL) was measured by an Accu-Chek® Aviva
self-monitoring device. Before and after a glucose drink (300ml solution, containing 75g of glucose (Accu-Chek®
Dextrose O.G.T.), BGL and FLIO were measured every 15min. The FLIMX software package was applied to
compute the average fluorescence lifetime τ on the inner ring of the ETDRS grid using a modified 3-exponential
Results: The results are given as mean ± standard deviation over all volunteers in ch1. Baseline measurement:
BGL: 5.3±0.4 mmol/l, τ1: 49±6ps. A significant reduction (α=5%; Wilcoxon rank-sum test) in τ1 is detected
after 15min (BGL: 8.4±1.1 mmol/l, τ1: 44±5ps) and after 90min (BGL: 6.3±1.4 mmol/l, τ1: 41±5ps). Results
of ch2 show smaller reductions in the fluorescence lifetimes over time.