Fluorescence lifetimes of drusen in age‐related macular degeneration

Abstract

PurposeFluorescence Lifetime Imaging Ophthalmoscopy (FLIO) allows non‐invasive in vivo measurement of fluorescence lifetimes of natural fluorophores of the retina upon excitation with a laser light. FLIO in different retinal diseases showed that the technique is useful to detect early metabolic changes and can differentiate between retinal deposits.The aim of this study was to characterize fluorescence lifetimes in retinal drusen due to age‐related macular degeneration (AMD).MethodsFLIO imaging was performed using a Fluorescence Lifetime Imaging Ophthalmoscope (Heidelberg Engineering, Germany). Autofluorescence was elicited with a 473 nm laser and decay times were measured in a short (498–560 nm) and in a long (560–720 nm) spectral channel. Fluorescence lifetime data was compared with autofluorescence intensity images, optical coherence tomography (OCT) and color fundus images. Soft drusen and reticular pseudodrusen were analysed and compared to an age matched control group.Results64 eyes from 64 patients with AMD and retinal drusen (age: mean ± SD 78 ± 8.5 years) were investigated and compared to 20 age matched healthy controls. Mean fluorescence lifetime in patients with AMD was significantly prolonged compared to the healthy control eyes (mean ± SEM; SSC 486 ± 18 ps vs 332 ± 11 ps, p > 0.0001; LSC: 493 ± 9 ps vs 382 ± 17 ps, p > 0.0001). Areas of drusen featured a broader range of fluorescence lifetime values. Long lifetimes were identified in areas of atrophy and intraretinal hyperreflective deposits. Areas of short lifetime corresponded to deposits within the photoreceptor outer segment band.ConclusionsMean retinal autofluorescence lifetimes in AMD were significantly prolonged compared to healthy control eyes. Intraretinal deposits caused prolonged lifetimes whereas deposits in the area of the outer photoreceptor segments lead to short fluorescence lifetimes.