First Author: C.Dysli SWITZERLAND
Co Author(s): S. Wolf M.S. Zinkernagel 0 0 0 0 0 0 0 0 0
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Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO) is used more recently for non invasive in vivo measurement of lifetimes of natural retinal fluorophores upon laser excitation. Fluorescence lifetimes are dependent of the metabolic environment such as the oxygenation level and the pH concentration. Therefore we aim to characterize fluorescence lifetimes of the retina after central artery occlusion.
This study was conducted at the department of ophthalmology at the University Hospital of Bern.
A Spectralis ® FLIO system (Fluorescence Lifetime Imaging Ophthalmoscope; Heidelberg Engineering, Germany) was used for fluorescence lifetime measurement of the ocular fundus. Fluorescence was excited using a picosecond laser at 473 nm wavelength. Decay times were measured in a short (498–560 nm) and in a long (560–720 nm) spectral channel. FLIO was performed in eyes after central retinal artery occlusion (CRAO) and compared to the contra lateral healthy eyes. Mean lifetimes were averaged within ETDRS grid areas (center, inner ring, outer ring).
In the short spectral channel, mean fluorescence lifetime values in the central area of the ETDRS grid were 296 ± 65 picoseconds (ps) (mean ± standard error of the mean) in eyes after CRAO and 231 ± 26 ps in the healthy control eyes (p=0.01). In the inner ETDRS ring, mean lifetimes were 455 ± 61 ps after CRAO and 323 ± 23 ps in control eyes (p=0.0006). In the long spectral channel, mean lifetimes in the central area were 357 ± 27 ps after CRAO and 341 ± 21ps in the control eyes (p=0.0006). In the inner ETDRS ring, mean lifetimes were 429 ± 26 ps after CRAO and 379 ± 22 ps in control eyes (p=0.0001).
Central retinal artery occlusion led to disease associated changes in fluorescence lifetimes of retinal fluorophores. Significantly longer lifetimes were observed in all ETDRS areas, potentially caused by altered cellular metabolism after retinal ischemia. In future, fluorescence lifetime measurement might be used for diagnostic purpose, disease and therapy monitoring, and might even have prognostic value.