Abstract
Purpose: :
To measure choroidal thickness (CT) in patients with geographic atrophy from age related macular degeneration using enhanced depth imaging optical coherence tomography (OCT).
Methods: :
This was a cross-sectional study. Nine consecutive eyes (mean age, 85 years; range 83-92 years) with geographic atrophy (GA) from AMD from the Massachusetts Eye & Ear Infirmary and the Luigi Sacco Hospital, University of Milan were enrolled. All patients underwent a clinical examination including color fundus photographs, fundus autofluorescence (FAF), optical coherence tomography (OCT), and enhanced depth imaging (EDI) of the choroid with the Heidelberg SpectralisTM. Horizontal images were obtained by positioning the spectral-domain OCT device close enough to the eye to acquire an inverted image. The horizontal B-scan at the level of the fovea was identified for analysis. GA boundaries were freehand traced on the FAF image and the total area of atrophy was measured using ImageJ software (http://rsbweb.nih.gov/ij/). Choroidal thickness (CT) was measured from Bruch’s membrane to the inner scleral border at the fovea, at point intervals 1000-µm and 2500-µm from the fovea in the nasal and temporal directions, at the borders of GA (as identified by FAF), and points 250 -µm outside the GA. The subfoveal, nasal and temporal 2500 µm CT points were compared to age-matched healthy eyes using an unpaired t-test.
Results: :
The mean area (mm2) of geographic atrophy on FAF was 365.56 ±113.50 mm2. The mean subfoveal CT was 171.56 µm ± 51.64 µm. The mean nasal CT at 2500 µm was 100.88 µm ± 58.74 µm. The mean temporal CT at 2500 µm was 167 µm ± 23.5 µm (p = 0.0016). Compared to normal healthy eyes, CT was decreased in all three areas of measurement in eyes with geographic atrophy, and this was statistically significant in the subfoveal (p=0.0001) and temporal (p=0.0016) areas, and approached significance in the nasal regions (p=0.08).
Conclusions: :
The subfoveal and temporal choroid is significantly thinner in patients with geographic atrophy in AMD compared to age-matched healthy eyes.
Keywords: age-related macular degeneration • choroid • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)