gms | German Medical Science

Both histological approaches and new imaging modalities reveal vascular loss in the choroid in AMD. Quantification of choroidal vascular lumen areas using a marker for viable endothelial cells shows loss of the choriocapillaris under intact RPE in early dry AMD, with more severe vascular degeneration in geographic atrophy. The observations that (a) choriocapillaris degeneration may precede RPE loss, (b) the membrane attack complex (MAC) of complement is predominantly localized to the choriocapillaris, (c) MAC is more abundant in eyes with AMD and in eyes with increased genetic risk for AMD, and (d) choroidal endothelial cells are susceptible to MAC-mediated lysis suggests a model for AMD pathogenesis in which injury to the choriocapillaris is an early event. This model for AMD pathogenesis will be discussed along with possible treatments for AMD by protecting the choriocapillaris in early AMD and rebuilding the choriocapillaris in late AMD, respectively.