Assessment of foveal sparing of reticular drusen in patients with age-related macular degeneration

Abstract

Purpose: To evaluate foveal sparing of reticular drusen (RDR) in patients with early age-related macular degeneration (AMD) using confocal scanning laser ophthalmoscopy (cSLO) and spectral-domain optical coherence tomography (SD-OCT).

Methods: Simultaneous combined near-infrared (NIR) cSLO and SD-OCT imaging (Spectralis, Heidelberg Engineering) was performed in 27 eyes of 21 patients (mean age 81 years, range 52 - 90) with RDR and early AMD. Early AMD was defined by the appearance of drusen or pigmentary changes but without signs of late AMD. The appearance and the distribution of RDR within the center macula were analyzed.

Results: RDR were detectable in NIR images as small hyporeflective lesions and larger hyporeflective rings with a hyperreflective center. In the corresponding SD-OCT scans, a wave-like pattern in the outer retina was noticed. A sparing of RDR with no visible individual lesions in the central macula was observed in 21 eyes, whereas the spared area circle size varied between 800 µm to 2000 µm. In 6 eyes, a few single RDR lesions were found within the 800 µm to 2000 µm diameter central circle, while RDR density (number of individual RDR per involved retinal area) was much higher towards eccentricity. In 12 eyes, foveal sparing of RDR with a horseshoe or incomplete ring appearance was present. The highest density was typically seen in the superior part, while the density tended to be lowest temporal and inferior to the fovea.

Conclusions: Foveal sparing of RDR is found in patients with nonexudative AMD. The findings are in accordance with a dynamic process of RDR evolution and involvement of the fovea not until later in the disease process. Factors for temporary sparing of the foveal retina are yet unknown, but may relate to different photoreceptor density and predominance of cones. Longitudinal studies with larger populations are warranted to further determine the natural history of variations in RDR distribution over time.

Keywords: 688 retina • 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 504 drusen