Abstract
Purpose: :
To compare melanin-related near-infrared fundus autofluorescence (NIA, excitation 787 nm, emission > 800 nm) to lipofuscin-related fundus autofluorescence (FAF, excitation 488 nm, emission > 500 nm) in patients with age-related macular degeneration (ARMD)
Methods: :
308 eyes of 172 patients with different stages of ARMD (age-related maculopathy (ARM, n=116), geographic atrophy (GA, n=77), neovascular ARMD (n=115) were diagnosed clinically and/or with fluorescein angiography (n=224). FAF and NIA imaging performed with a confocal scanning laser ophthalmoscope (Heidelberg Retina Angiograph 2). Presence, pattern and size of retinal pigment epithelial (RPE) alterations detected with FAF and NIA
Results: :
Alterations of FAF and NIA were observed in all eyes included in this study. In the majority of eyes (81.8%), the lesion size was similar in both methods. In ARM spots of increased FAF were more frequent then spots of reduced FAF (87.9% vs. 26.7%), whereas spots of increased and reduced NIA were of similar frequency (66.4%). Spots of increased FAF corresponded to either increased, normal or reduced NIA indicating different pathophysiologic conditions. Spots with a higher relative intensity of FAF compared to NIA (increased FAF and normal or reduced NIA or normal FAF and reduced NIA) were more frequent (72.4%) compared to spots with higher relative NIA intensity (16.4%) suggesting that loss of NIA usually precedes loss of FAF. In GA, atrophic areas corresponded to absent FAF and NIA. The junctional zone of GA showed increased NIA in 41.6%, increased FAF in 32.5% and only in 22.1% an increase of both FAF and NIA indicating different pathophysiologic processes. In neovascular ARMD, FAF (68.7%) and NIA (81.7%) can be blocked by exudation and blood. Exudative changes were better visualized with FAF compared to NIA (56.5 vs. 33.9%).
Conclusions: :
NIA imaging provides a non-invasive in vivo visualization of RPE abnormalities. Patterns of FAF and NIA indicate different involvement of lipofuscin and melanin and their related derivates in the pathophysiological process. Combined FAF and NIA imaging will provide further insight in the development of ARMD and could help to monitor future therapeutic interventions.
Keywords: age-related macular degeneration • retinal pigment epithelium • macula/fovea