First Author: M.Lindner GERMANY
Co Author(s): A. Bezatis J. Czauderna R. Fimmes S. Schmitz-Valckenberg F. Holz M. Fleckenstein 0 0 0 0 0 0 0 0 0
Back to previous
To analyze choroidal thickness (CT) in eyes with geographic atrophy (GA) secondary to AMD in relation to fundus autofluorescence (FAF) phenotype and GA lesion size, respectively.
Patients with GA in at least one eye participating in the ‘Directional Spread in Geographic Atrophy’ trial (‘DSGA’, NCT02051998, extension trial of the FAM study NCT00393692). Patients without retinal disease of similar age were recruited at the Department of Ophthalmology, University of Bonn, Germany to serve as controls.
CT was analyzed in vertical and horizontal enhanced depth imaging (EDI) spectral domain optical coherence tomography (SD-OCT) images (Spectralis HRA+OCT, Heidelberg Engineering, Germany). Measurements of CT (26 per eye) were taken subfoveally and each 500 µm from the center to an eccentricity of 3000 µm. The overall CT of an eye was calculated by averaging these 26 single CT measurements. Phenotyping of GA was based on confocal scanning laser FAF (exc. 488nm, em. > 500nm) according to the previously introduced FAM study classification (Holz et al. AJO 2007). GA size was determined in FAF images by semi-automated analysis software (RegionFinder, Heidelberg Engineering).
A total of 51eyes (51 patients, mean age 76.84±7.23) with GA and 31 eyes (31 patients, mean age 75.56±6.43) without retinal diseases were included into the analysis. There was a significantly thinner choroid in eyes with GA as compared to controls (168.29±82.22 µm vs. 216.15±56.23 µm, p=0.005). Within the group of GA, patients with the ‘diffuse-trickling’ FAF phenotype (n=9) exhibited a significantly thinner choroid compared to patients with ‘non-diffuse-trickling’ GA (115.85±34.75 µm vs. 179.53±85.02 µm, p=0.046). The difference in CT between ‘non-diffuse-trickling’ GA (n=42) and controls was not significant (p=0.081). There was a mean atrophy size of 6.84±5.8 mm² at time of CT measurement. Regression analysis revealed no correlation between GA size and CT (R=0.034).
The results demonstrate that CT is decreased in eyes with GA as compared to eyes without retinal disease. However, this observation seemed to be driven by markedly thinned choroids observed in the “trickling”-phenotype. While CT was associated with the FAF phenotype of GA, there seemed to be no general dependency between CT and size of atrophy. This may point to differential role of the choroid in distinct GA subtypes. Refined phenotyping including FAF imaging appears prudent in ongoing and future studies to identify different GA phenotypes and to further explore discriminating features.