Changes in Subretinal Drusenoid Deposits (SDD) During Progression to Geographic Atrophy (GA) and Choroidal Neovascularization (CNV) in Age-Related Macular Degeneration (AMD)

Abstract

 

Purpose

 

This retrospective study utilized 3 imaging modalities to quantitatively analyze SDD evolution in eyes that progressed from early to late AMD over a 2-year follow-up period. We analyzed the change in SDD area within the fundus, both in subjects who progressed to GA and in those who progressed to CNV, with the goal of better understanding the dynamic spatiotemporal nature of SDD and their role in AMD progression.

 

Methods

 

25 patients with AMD and unilateral CNV were included. The non-CNV eyes (the study eyes) all underwent indocyanine green angiography (ICG), short-wavelength autofluorescence (AF), and near infrared reflectance (NIR) imaging at baseline and at 2-year follow-up. Study eyes were analyzed for SDD and for the development of late AMD—both CNV and geographic atrophy (GA). SDD area measurements were obtained by two graders utilizing ImageJ software and are expressed as a percentage of total fundus area; binary logistic regression and the Wilcoxon nonparametric test were used for statistical analysis.

 

Results

 

8 study eyes developed GA and 17 study eyes developed CNV during the follow-up period. In the eyes that developed CNV, there was a statistically significant decrease in SDD area as seen on AF (P=0.004) and NIR (P=0.027), and the decrease in SDD area approached statistical significance on ICG (P=0.078). By contrast, in the eyes that developed GA, there was no significant change in SDD area as seen on all 3 imaging modalities (ICG: P=0.75, AF: P=0.275, and NIR: P=1).

 

Conclusions

 

SDD undergo dynamic spatiotemporal changes in eyes with AMD. These lesions can be seen in eyes that progress to late AMD, both GA and CNV, but a decrease in SDD area is seen only during progression to CNV, likely as a result of worse ischemia and increased VEGF in CNV subjects. These results suggest that the SDD lesions migrate, are absorbed by surrounding cells, or are no longer visible due to imaging difficulties secondary to changes present in CNV.  

 

All images are from the same subject; A-C at initial imaging, D-F at final follow-up. A&D=ICG, B&E=AF, C&F=NIR