Location, substructure, and composition of basal laminar drusen compared with drusen associated with aging and age-related macular degeneration

PURPOSE: To determine whether basal laminar drusen differ in their location , ultrastructure, or composition from drusen associated with aging and age- related macular degeneration. METHODS: A paraffin-embedded block from an eye of a patient with basal lami nar drusen was obtained. Sections were examined immunohistochemically using a battery of antibodies and lectins directed against drusen-associated pro teins and glycoconjugates, respectively. Thin sections were examined by ele ctron microscopy and compared with eyes with age-related macular degenerati on. RESULTS: Drusen in the eye with basal laminar drusen are located between th e basal lamina of the retinal pigment epithelium and the inner collagenous layer of Bruch membrane, just as they are in age-related macular degenerati on. Two distinct ultrastructural phenotypes are observed in the eye with ba sal laminar drusen; their substructure is indistinguishable from drusen phe notypes in age-related macular degeneration. Both basal laminar drusen and drusen associated with age-related macular degeneration are bound by the le ctins Ricinis communis agglutinin and Arachis hypogea agglutinin (after neu raminidase digestion) and by antivitronectin, anti-HLA-DR, anti-serum amylo id P, and anti-C5 antibodies, but not by antibodies directed against baseme nt membrane-associated heparan sulfate proteoglycan, laminin, fibrinogen, o r collagen type IV. CONCLUSIONS: These data support the notion that cuticular or basal laminar drusen are similar to, and perhaps indistinguishable from, drusen associate d with age-related macular degeneration and are not nodular or diffuse thic kenings of Bruch membrane, as previously suggested. Thus, we suggest basal laminar drusen is a misnomer. This clinical phenotype should be identified as "early adult onset, grouped drusen" or by the eponym "Gass syndrome." Fe atures of basal laminar drusen, such as uniform drusen size, clustered dist ribution, and angiographic features, do not appear to be related to differe nces in drusen location, composition, or substructure. (Am J Ophthalmol 200 0;129:205-214. (C) 2000 by Elsevier Science Inc. All rights reserved.)