Drusen and autofluorescence co–localization in early and late age–related macular degeneration.

Abstract

Abstract: : Purpose: To measure patterns of hyperfluorescence in relation to drusen and GA in Stage 3 and 4 AMD. Methods: Color fundus photographs and scanning laser ophthalmoscope (SLO) images of patients with age–related macular degeneration (AMD) were analyzed. Drusen and hyperautofluorescence (hyperAF) were identified in eleven pairs of images (6 patients) with Stage 3 AMD (large soft drusen) and in nine pairs of images (five patients) with Stage 4 AMD (large soft drusen and geographic atrophy (GA)). The photographic and SLO images were precisely registered using Matlab for lesion co–localization. In stage 3, drusen and hyperAF were segmented in the central 3000 microns by a semi–automated technique based on leveling the macular background with a mathematical model. In Stage 4, segmentation was done over a 6000–micron region by local thresholds. Results: In stage 3 AMD, 76.71 % ±15.74 (1stdev) of hyperAF co–localized with drusen and in stage 4 AMD, 12.48% ± 11.26 (1stdev) of hyperAF co–localized with drusen (p = 0.000000090). In stage 4, 58.74%±22.16 (1stdev) of hyperAF occurred in crescents around GA, and distinct hyperAF was often seen adjacent to but rarely in drusen. Conclusions: Focal lipofuscin accumulation in AMD as measured by autofluorescence largely co–localizes with soft drusen in stage 3 and then is found mostly adjacent to, but not within GA and drusen in stage 4. This suggests that dispersal of drusen–associated lipofuscin may be a marker for disease progression in AMD.

Keywords: age–related macular degeneration • image processing • drusen