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M.A. Williams, V. Silvestri, D.C. Henderson, P.J. Brogan, G. Silvestri; A New Subclass of Very Small Drusen Is Prevalent in the Under 50 Age–Group . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2129.
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While there is abundant information on the prevalence of drusen in the elderly, data on drusen in those under 50 years old is relatively lacking. We have previously reported the prevalence of drusen in the under–50's. Our data indicated that most drusen in the under 50’s were < 63 µm. An additional observation was that although these drusen were classified in the <63 µm group, most were much smaller and perhaps were of lesser significance. A new subgroup of drusen was therefore defined; those 31.5 µm or less in diameter. The prevalence of this new very small drusen subclass in the under 50’s was measured.
We reviewed digital retinal images (taken using the non mydriatic Canon CR–DGi) from both eyes of 500 consecutive patients aged 20–49 from local optometry practices. The patients had been photographed routinely as part of their examination and were therefore representative of the general population. The images were anonymized, data recorded being date of birth and a code number for the image. The images were graded for the presence, size and number of drusen within the 6000 µm standard AREDS grid. 31.5 µm, 63 µm, 125 µm and 250 µm circles were drawn using Adobe Photoshop and were calibrated for 45 degree Canon images.
Analysis of a subgroup of the total number of patients was performed and the following results were obtained. 46.7% of all eyes graded in all age groups had macular drusen of any size. The most common size of drusen was the very small subclass, i.e. < 31.5 µm in diameter. The prevalence of drusen by size is shown in Table 1. Table 1. Prevalence of drusen by size.
18.9% of eyes in total had only very small drusen (<31um).
Drusen are common in the under 50’s. A previously unreported very small subclass of drusen is the most common subtype, i.e. under 31.5 µm in diameter. This finding allows refinement of the phenotyping of individuals in younger generations in AMD families.
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