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M. Rudolf, M. F. Chimento, L. Wang, M. E. Clark, J. Messinger, C. A. Curcio; Ultrastructural Morphology of Druse Types in the Macula and Periphery of Eyes With Age-Related Maculopathy (ARM). Invest. Ophthalmol. Vis. Sci. 2009;50(13):4932.
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© ARVO (1962-2015); The Authors (2016-present)
To describe ultrastructural differences among druse types found in the macula (soft and hard) and periphery (hard and compound), as previously defined by light microscopy (Rudolf et al., 2008), in eyes with early ARM.
Drusen were isolated manually from the macula (n=77) and the periphery (n=195) of 9 paraformaldehyde /glutaraldehyde-preserved eyes (age 69-102 yr) with grossly visible early ARM. Pelleted-drusen were post-fixed in osmium, embedded in epoxy resin, and sectioned for transmission electron microscopy. The presence of 9 druse constituents and basal laminar deposits (BlamD) was assessed semi-quantitatively in each druse. We report the percentage of drusen at each location, pooled across eyes, in which particular features were abundant.
Early BlamD was equally present in the macula (65 %) and periphery (70 %), but late BlamD was predominately found in the macula (16 % vs. 2 %) of ARM eyes. All drusen types demonstrated a specific profile of constituents. Only dense particles (~47 %) and lipid pools (~16 %) were abundantly found in all drusen types. Soft drusen, present only in the macula, exhibited typically numerous membranous profiles with or without content (58 %). Hard drusen, found at both locations, had usually a homogenous background (63 %) and many dense particles (60 %). Macular hard drusen exhibited also one abundant material likely to represent calcifications (24 %). Compound drusen, which were present only in the periphery, exhibited most often coiled membranes (41 %).
At light microscopic level defined drusen types exhibited also type-specific ultrastructural differences. Even though some constituents are common druse material, others dominate in one druse type. Macular soft drusen appear more loosely packed, containing an electron-dense membrane-like material barely apparent in peripheral drusen. Also late BlamD is quite restricted to the macula, which might help explain why the macula is more susceptible to advanced ARM than the periphery.
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