Abstract
Purpose :
Drusen are a hallmark of age-related macular degeneration (AMD). We and others have previously shown the outer retina overlying drusen is thinned compared to adjacent drusen-free areas. This study determines how retinal thinning relates to the natural history of drusen (i.e. drusen regression).
Methods :
Spectral domain optical coherence tomography (SD-OCT) scans from the Heidelberg Spectralis SD-OCT of early to intermediate AMD patients seen at the Centre for Eye Health between 2010-15 were reviewed and drusen which had progressed or regressed identified (n = 125 single druse, 45 confluent druse, 49 regressing druse). Thickness of individual retinal layers was measured using the automated segmentation software of the Spectralis SD-OCT, manually adjusted for any incorrect segmentation (termed-semi-automated segmentation). Thickness above the druse was compared to a drusen-free area, 150µm from the drusen edge.
Results :
Automated segmentation produced numerous errors over drusen in the RPE (98% error rate) and thus semi-automated segmentation was performed for all measurements. This method found significant thinning of the RPE (28.9 ± 1.8%), photoreceptor (23.8 ± 1.3%) and outer nuclear layer (ONL; 27.4 ± 1.2%) above single, isolated druse which was comparable to manual measurements on the same drusen population. Thickness of retinal layers returned to baseline with drusen regression except the ONL which remained significantly thinned (10.6 ± 2.9%; p < 0.05) compared to drusen-free areas.
Conclusions :
We confirmed thinning of the outer retina layers above isolated and confluent drusen and showed thinning of the ONL remains after drusen regression. This may indicate why drusen regression has been previously associated with disease progression. We also show automated segmentation by the Spectralis SD-OCT software requires operator intervention to correct for segmentation errors.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.