Abstract
Purpose: :
To investigate the ability of the spectral-domain optical coherence tomography to describe reliably and reproducibly the geometry of drusen in patients with non-exudative age-related macular degeneration (AMD).
Methods: :
A Spectral-domain Optical Coherence Tomography (a prototype of the Cirrus HD-OCT, from Carl Zeiss Meditec, Inc) system was used to obtain three-dimensional data sets covering a 6x6 mm region of the macula The patients were scanned multiple times at baseline and again at each follow-up visit. Custom-designed software was used to analyze the scans. This tool automatically identified the retinal pigment epithelium (RPE) and a surface corresponding to Bruchs membrane where the RPE is perturbed. Several quantitative descriptors of drusen geometry in three dimensional space, in particular drusen area and volume, were produced. These quantitative descriptors were compared with standard measurements of drusen from fundus photography.
Results: :
Fifty patients with non-exudative AMD were scanned. Our software allowed us to visualize, measure, and monitor over time subtle changes in retinal geometry. In particular, we developed novel quantitative descriptions of the properties of drusen and their effect on the RPE. The automatic segmentation agreed with manually drawn boundaries (average difference less than 6 microns). The measurements were both qualitatively and quantitatively reproducible (coefficient of variation less than 10%).
Conclusions: :
SD-OCT provided high speed and quality 3-D images of retinal morphology from which unprecedented, quantitative descriptions of drusen geometry were generated. Our results were reproducible and correlated well with classic fundus photographic analyses. This approach has the potential to be an important tool in improving our understanding the progression of non-exudative AMD.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • age-related macular degeneration • retina