Abstract
Purpose: :
To assess the association of calcified drusen with progression of AMD, and to illustrate the course of such eyes, in the Age–Related Eye Disease Study (AREDS).
Methods: :
Calcified drusen are small refractile deposits associated with AMD, particularly geographic atrophy (GA). We compared 5–year rates of progression to advanced AMD (neovascular AMD and/or central GA), and to the development of noncentral GA, in eyes with and without calcified drusen. We limited the analysis to eyes that at baseline (a) were in AREDS category 3 (having at least one large ordinary druse [>= 125µm] or extensive intermediate drusen), (b) did not already have non–central GA, and (c) had 5 years of follow–up. We used the extended AREDS severity scale to concentrate this analysis on eyes in levels 6–8, defined as having extensive drusen area and/or pigment abnormalities but without GA. Because both eyes of one subject could have calcified drusen, we present our results based upon only right eyes.
Results: :
Among 1086 right eyes in AREDS category 3, 75 eyes (4%) had calcified drusen and 2069 eyes (96%) did not. Progression rates to advanced AMD were 39% vs.13% respectively (p<0.0001 by chi–square). Dividing these progressions, neovascular AMD rates were 13% vs. 8%, central GA rates were 26% vs. 5%, and neoAMD with GA rates were none vs. 1%, respectively. Non–central GA incidence rates were 37% vs. 8%, respectively. Restricted to the 555 right eyes in AREDS levels 6–8, 38 eyes (7%) had calcified drusen and 517 eyes (93%) did not, with progression rates to advanced AMD of 39% and 25%, respectively, (p < 0.0001). Neovascular AMD rates were 13% vs. 14%, central GA rates were 26% vs. 9%, and neoAMD with GA rates were none vs. 2%, respectively. Non–central GA incidence rates were 37% vs. 13%, respectively. Considering the left eye of these 38 subjects with calcified drusen in their right eye, 36 (95%) also had this finding in their contralateral eye. Conducting the outcome analysis for left eyes yielded results very similar to those for right eyes.
Conclusions: :
AREDS results show that presence of calcified drusen at baseline signifies 3– to 4–fold increased risk for 5–year progression to geographic atrophy, both central and non–central.
Keywords: age-related macular degeneration • drusen • clinical (human) or epidemiologic studies: risk factor assessment