Purpose:
To determine fundus autofluorescence (FAF) signal variability and corresponding microstructural alterations on spectral-domain optical coherence tomography (SD-OCT) in areas of funduscopically visible drusen associated with age-related macular degeneration (AMD).
Methods:
Retinal imaging data of 30 eyes from 22 patients with geographic atrophy secondary to AMD (median age 74, range 64-87 years) including colour fundus photography (CFP), combined confocal scanning laser ophthalmoscopy (FAF, exc. 488nm, em 500-700nm) and SD-OCT (870nm) (Spectralis HRA+OCT, Heidelberg Engineering) were analyzed. In each eye, at least one soft druse (> 63 µm) recorded on CFP was selected. Relative FAF intensities and changes in SD-OCT bands at the site of each druse were evaluated.
Results:
A total of 73 soft drusen were analyzed showing similar appearance of yellowish-white deposits in CFP, while variable corresponding alterations were present on both FAF and SD-OCT scans. FAF signal was normal, increased, decreased or not evaluable in 32, 27, 12 and 2 drusen respectively. In all cases, SD-OCT scans showed an elevation of bands 1-4 by sub-RPE material. Focal hyperreflectivity above band 4 up to the outer nuclear layer (ONL) was most frequently correlated with increased FAF (present in 9%, 33%, 16% of drusen with normal, increased and decreased FAF respectively). ONL thinning (present in 0%, 4%, 58%) and choroidal hyperreflectivity (present in 3%, 4%, 50%) were associated with decreased FAF.
Conclusions:
CFP recording of soft drusen may not allow for differentiation between preserved and markedly compromised outer retinal integrity including incipient atrophy and focal neurosensory alterations of reflectivity overlying extracellular sub-RPE deposits. In contrast, multimodal imaging reveales a broad spectrum of microstructural findings that may indicate different drusen development stages and/or soft drusen phenotypes.
Keywords: age-related macular degeneration • drusen • imaging/image analysis: clinical