Assessment of the Relationship Between Choroidal Thickness and Drusen Burden in Non-neovascular Age-related Macular Degeneration

Abstract

 

Purpose

 

Previous research has suggested that choroidal thinning occurs with increasing age. Age-related choroidal atrophy has been previously described as a clinical entity with significant choroidal thinning and a paucity of drusen that may mimic non-neovascular age-related macular degeneration (NNVAMD) or simply be part of the AMD spectrum. This study was performed to assess the relationship between choroidal thickness and drusen burden in eyes presenting with a clinical diagnosis of NNVAMD.

 

Methods

 

This is a retrospective, consecutive case series of patients with at least one eye with a clinical diagnosis of NNVAMD as determined by one of two retinal specialists. Imaging was performed using the Cirrus HD-OCT (Carl Zeiss Meditec, Dublin, CA). Subfoveal choroidal thickness was measured on the high resolution raster or enhanced depth imaging (EDI) scan. The advanced retinal pigment epithelium (RPE) analysis algorithm was utilized to calculate the central 5-mm drusen area and volume. Clinical variables collected included visual acuity, lens status and refraction. Patients were excluded if they had subfoveal geographic atrophy or evidence of any other retinal disorder including: neovascular AMD, prior macular laser therapy, high myopia, uveitis or prior vitreoretinal surgery.

 

Results

 

183 eyes from 123 patients were included in the analysis. Mean logMAR visual acuity was 0.129 (Snellen equivalent 20/27) with a mean age of 77 years. Mean central retinal thickness was 221.2 microns, and mean manual subfoveal choroidal thickness was 191.1 microns. Mean drusen area and volume in the 5mm ETDRS circle centered on the fovea was 0.54mm² and 0.21mm³, respectively Choroidal thickness was negatively correlated with drusen area (r=-.2869, p < 0.001) and drusen volume (r=-.2205, p = 0.0024).

 

Conclusions

 

Choroidal thickness appears to be inversely correlated with drusen burden in eyes with non-neovascular age-related macular degeneration in the absence of subfoveal geographic atrophy. The relationship of drusen burden to choroidal thickness deserves further investigation in the pathogenesis of NNVAMD in order to further understand the place of age-related choroidal atrophy in the AMD spectrum.

 

Keywords: 412 age-related macular degeneration • 550 imaging/image analysis: clinical • 688 retina