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P. Jagananthan, L.B. Kibel, A.O. Edwards; Longitudinal monitoring of drusen features using infrared reflectance imaging: analysis of drusen in the fellow eye of subjects with unilateral exudative age–related macular degeneration . Invest. Ophthalmol. Vis. Sci. 2004;45(13):2986.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Objective and quantitative endpoints are needed for evaluation of potential therapies for age–related macular degeneration (AMD). Ideally, methods for monitoring would be non–invasive and capable of detecting changes in natural progression of disease over short periods of time. We have been evaluating infrared reflectance (IR) imaging of drusen features to determine if this method–endpoint combination could be used to meet this goal. Methods: Eleven patients with ages ranging from 55–86 having exudative AMD in one eye and early, non–exudative AMD in fellow eye meeting specific study criteria at baseline were identified. The study criteria included availability of IR images (SLO at 830 nm) and absence of potentially confounding diseases. Baseline drusen features and longitudinal changes were studied by (i) clinical interpretation of original IR images and (ii) pseudocolor intensity profiles. Results: Inspection of the IR images revealed a characteristic reflectance pattern from drusen that we describe as dark spots with halo. Longitudinal changes were observed in individual drusen–specific features including (i) increased amplitude of the difference in reflectance between the dark center and surrounding area of hyperreflectance (halo) and (ii) increased reflectance of drusen leading to easier recognition. New reflectance abnormalities compatible with drusen were seen leading to a modest increase in drusen number and area of fundus involvement. Graphical analysis of pseudocolor intensity surface profiles of selected regions were adjusted for differences in image acquisition gain. Intensity profiles enhanced visualization of longitudinal changes in individual drusen–specific features and would enable development of quantitative approaches. The intensity profiles also were consistent with global changes in spatial frequency domain patterns. In order to begin to quantify longitudinal changes in drusen features, we selected maximal vertical drusen diameter for detailed study. Specific drusen in the macula from 3 patients were measured at baseline and then at follow–up. The mean change in drusen diameter was observed to increase at a mean rate of approximately 1.7 µm/month. Conclusions: IR imaging is a promising tool for quantifying longitudinal changes in features presumed to arise from specific drusen. IR imaging may ultimately provide a measure of global changes across the macula arising from the accumulation of subretinal deposits that lead to clinically recognizable drusen.
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