Research Perspective Volume 1, Issue 8 pp 740—745

Figure 1. Diagram illustrating the progression of early age related macular degeneration (AMD) into 2 divergent late stages and the potential role of BMP4 as a switch between these pathways. Chronic stressors such as oxidative stress can promote the expression of BMP4 in the retinal pigment epithelium (RPE) and induce RPE senescence as part of the phenotype of early AMD. If BMP4 expression is sustained, it could lead to RPE apoptosis and geographic atrophy. In other individuals, activation of the senescence activated secretory pathway and expression of pro-inflammatory mediators could result in increased expression of interleukin (IL)-8, decreased expression of BMP4 and increased expression of vascular endothelial growth factor (VEGF) resulting in neovascular AMD with choroidal angiogenesis.