Abstract
Purpose: :
To determine microstructural correlates on spectral-domain optical coherence tomography (SD-OCT) of areas with increased fundus autofluorescence (FAF) in the perilesional zone of geographic atrophy (GA) due to age-related macular degeneration (AMD).
Methods: :
In a prospective longitudinal study (FAM study, NCT00393692), 120 eyes of 67 patients (mean age 76.1±8.6 years) with uni- and multifocal GA due to AMD were examined by simultaneous confocal scanning laser ophthalmoscopy and high-resolution SD-OCT (Spectralis HRA+OCT, Heidelberg Engineering). FAF patterns with dependent progression-rates were classified as previously described (Am J Ophthalmol. 2007;143:463-72). Corresponding microstructural changes of the outer retinal layers were evaluated in SD-OCT scans.
Results: :
FAF patterns were classified into "focal" (7 eyes, 5.8%), "banded" (14 eyes, 11.6%), "patchy" (6 eyes, 5%), "branching" and "reticular" (33 eyes, 27.5%), "fine-granular" (37 eyes, 30.8%), "GPS" (4 eyes, 3.3%), and "trickling" (18 eyes, 15%); one eye displayed no abnormal FAF. SD-OCT revealed clearly definable outer retinal layers without marked alterations in areas with a normal FAF signal. Circumscribed lesions with intensive increased FAF in eyes with "focal", "branching", "reticular" and "GPS" FAF patterns, correlated with hyperreflective material that was located between the retinal pigment epithelium/Bruchs membrane- (RPE/BM) and outer nuclear layer-level. Areas with increased FAF at the GA border in eyes with the "banded" pattern and in a more widespread area in eyes with the "fine-granular" and "trickling" FAF pattern correlated with a thickened RPE/BM layer, frequently with apical extension. In areas of increased FAF, the integrity of the photoreceptor inner segment/outer segment layer was severely disturbed. A splitting of the RPE/BM layer in the perilesional zone through the border was most obvious in eyes displaying the "trickling" FAF pattern with the highest progression-rate.
Conclusions: :
In areas with increased FAF outside areas of GA, SD-OCT imaging reveals marked morphological abnormalities not only of the RPE cell layer but also of outer layers of the neurosensory retina. Pronounced photoreceptor layer alterations may indicate a pathophysiological role early in the disease process in areas of incipient atrophy identified by FAF imaging. In longitudinal studies, combined FAF and SD-OCT imaging may add to the spectrum of biomarkers for lesion growth.
Clinical Trial: :
www.clinicaltrials.gov NCT00393692
Keywords: age-related macular degeneration • imaging/image analysis: clinical • retinal pigment epithelium