Abstract
Purpose: :
To characterize the natural history of drusen using spectral-domain optical coherence tomography (SDOCT) imaging of eyes from patients with non-exudative age-related macular degeneration (AMD).
Methods: :
143 eyes of 100 patients with drusen secondary to non-exudative AMD were scanned using the Cirrus SDOCT instrument (Carl Zeiss Meditec, Dublin, CA). Eyes were imaged using the 200 X 200 A-scan raster pattern covering a 6mm X 6mm area. Custom software was used to quantify volumetric changes in drusen over a period of at least 6 months and for as long as 24 months. Drusen volume and drusen area were measured within circular regions centered at the fovea having diameters of 3mm and 5mm. The measurements were analyzed using a suitable transformation strategy; the cube-root was used for drusen volume measurements.
Results: :
The 3mm circle baseline drusen volume ranged from 0.0009 mm3 to 0.7479 mm3 or 0.10 mm to 0.91 mm using the cube root scale. On average, drusen volume and drusen area increased over time with the magnitude of the increase dependent on the length of follow-up (p=0.001, 3mm circle). In the eyes with a decrease in drusen volume, the magnitude of this decrease was dependent on the baseline drusen volume (p=0.001, 3mm circle) and independent of the follow-up interval.
Conclusions: :
SDOCT imaging of drusen revealed that drusen morphology is dynamic with a tendency to increase in volume and area over time. An appreciation of the quantitative changes in drusen volume over time using SDOCT imaging provided a novel strategy for following normal disease progression and for identifying novel clinical trial endpoints when investigating therapies for the treatment on non-exudative AMD.
Keywords: drusen • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • age-related macular degeneration