IL18 and atrophic macular degeneration: Thus it appears, in this specific instance, that IL-18, which is constitutively produced by the RPE cell (Jiang et al., 2001), acts as a regulator of RPE function and determines whether the RPE cell succumbs to aging stress (para-inflammation) and dies (geographic atrophy) while attempting to prevent an angiogenic response to an increasing age-related pro-inflammatory microenvironment.