Identification of Drusen Characteristics in Age-Related Macular Degeneration by Polarization-Sensitive Optical Coherence Tomography

PURPOSE: To describe qualitative characteristics of drusen in eyes with nonadvanced age-related macular degeneration (AMD) using polarization-sensitive optical coherence tomography (OCT). DESIGN: Cross-sectional study. METHODS: Twenty-five eyes of 25 patients with early to intermediate (nonadvanced) AMD were imaged with polarization-sensitive OCT using macular volume scans. All individual drusen in each B-scan were manually delineated by experts certified by a reading center and graded for 6 different morphologic characteristics based on a defined classification scheme, including the presence of internal depolarizing structures and associated depolarizing foci. With the use of a custom-made software, the central B-scan of each individual druse was selected and used to analyze its location, diameter, and characteristics and assess the prevalence of the different features and relations between them. RESULTS: Using the macular volume scans, 6224 individual drusen could be identified, including their position within the retina, their characteristics, and their association with any pigmentary alterations. The most common drusen type was a convex-shaped druse with homogeneous medium internal reflectivity and no depolarizing contents (55.3% of drusen). A total of 30.5% of the drusen exhibited internal depolarizing material; 0.3% presented overlying hyperreflective foci, and in 54.5% the foci were also depolarizing. Significant correlations were found between the diameter of the drusen and their distribution throughout the retina, shape, homogeneity of internal reflectivity, presence of internal depolarizing characteristics, and presence of overlying foci (P < .001 each). Significant relations were found between reflectivity, homogeneity, and polarization-sensitive internal characteristics (P < .001). CONCLUSIONS: Polarization-sensitive OCT reveals characteristic morphologic features of different druse types highlighting the pathophysiological spectrum of early to intermediate AMD.