Abstract
Purpose: :
To demonstrate and quantify the dynamic remodeling process of soft drusen resorption and new drusen formation in AMD.
Methods: :
17 patients with large soft drusen OU and without advanced AMD in the Columbia Macular Genetics Study were imaged at baseline and again at a mean interval of 2 years. Each of the 34 serial pairs of images was precisely registered in Matlab, and the drusen were segmented in the 3000 diameter circle (central region) and the 3000-6000 micron annulus (peripheral region) by automated methods described previously (Smith RT et al. Automated Detection of Macular Drusen using Geometric Background Leveling. Arch Ophthalmol, 2005). The initial (D0) and final (D1) drusen segmentations then provided an immediate classification of drusen (or parts of drusen) into three groups: new drusen (present only in D1), resorbed drusen (present in D0 but not in D1) and old drusen (present in both images). If the net change in drusen was D1 - D0, then the dynamic change in drusen was restated as D1 - D0 = Dnew - Dresorbed, which we calculated in the central and peripheral regions
Results: :
Large soft drusen tended to disappear centrally (-21.0 to +0.3 %/yr, median = -2.2 %/yr) and develop peripherally (-0.3 to 8.1 %/yr, median = 0.3 %/yr) at rates (% of central or peripheral region per year) that varied significantly between patients.
Conclusions: :
Remodeling of soft drusen can be quantified by the dynamic variables of new and resorbed drusen. Both are measures of distinct disease activities that are not captured by total drusen load. While it is accepted that large soft drusen tend to disappear centrally and develop peripherally in eyes progressing to central atrophy, these data suggest that this is is a more universal property of soft drusen in progressive AMD, with rates that vary significantly between patients.
Keywords: drusen • imaging/image analysis: clinical • age-related macular degeneration