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M. Fleckenstein, H. M. Helb, P. Charbel Issa, R. P. Finger, K. Löffler, H. P. N. Scholl, S. Schmitz-Valckenberg, F. G. Holz; Geographic Atrophy Assessment With Combined High-Resolution SD-OCT and Simultaneous cSLO Fundus Autofluorescence Imaging. Invest. Ophthalmol. Vis. Sci. 2008;49(13):257. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To correlate variations in confocal scanning laser ophthalmoscopy (cSLO) fundus autofluorescence (FAF) with morphological findings visualized in vivo by spectral domain optical coherence tomography (SD-OCT) in eyes with late atrophic AMD using a novel instrument for simultaneous cSLO and SD-OCT imaging.
Combined cSLO FAF (exc. 488nm, em. > 500nm) and SD-OCT (870 nm, 40.000 A-scans/sec) imaging was performed with the Spectralis HRA-OCT (Heidelberg Engineering, Heidelberg, Germany). While an automated eye tracking system corrected for eye movements locations of OCT scans were manually chosen to allow for pixel-to-pixel correlation at sites of interest based on findings in the FAF scanning mode. 70 eyes of 49 patients (mean age 77.9 ±7.6 years) with uni- or multifocal geographic atrophy (GA) associated with AMD were examined.
Areas of GA were accurately delineated on FAF images. Complete loss of RPE cells, photoreceptors, external limiting membrane (ELM) and outer nuclear layer over the entire atrophic area was noted in 8 eyes (11.4%). In 62 eyes (88.6%) GA exhibited irregularly increased FAF with corresponding hyperreflective clumps at the RPE level. In 22 eyes (31.4%) drusen-like material was present scattered throughout the atrophic area. While photoreceptors and ELM were not delineated overlying such focal lesions, hyperreflective dots were occasionally noted anteriorly in various layers of the neurosensory retina. Increased FAF at the border of GA and in the perilesional zone was associated with variable alterations including sub-RPE deposits, thickening of the RPE layer, hyperreflective bands overlying sub-RPE deposits and clumps located in variable anatomic layers of the neurosensory retina.
The combined imaging technique applied herein allowed to investigate morphological substrates for alterations identified in FAF images in eyes with GA. The findings indicate that identically appearing FAF phenomena on two-dimensional cSLO FAF images may have highly variable underlying morphological substrates at different anatomical retinal levels on corresponding SD-OCT scans. This may either reflect different stages in a uniform dynamic process leading to outer atrophy, or may, alternatively, indicate heterogeneity on a molecular and cellular level. Longitudinal investigations using the new combined SLO-OCT imaging technology will further add to the understanding of GA pathogenesis including the role of excessive lipofuscin accumulation in the RPE.
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