Pegaptanib (Macugen, Bausch + Lomb Pharmaceutical Retina Portfolio, FDA approval in December 2004) is a 27 base RNA aptamer (see Figure 4 for predicted structure, Ng et al., 2006) selected against vascular endothelial growth factor (VEGF) and is used to treat age-related macular degeneration, a leading cause of irreversible blindness worldwide (Ruckman et al., 1998). Here, VEGFA is linked to age-related macular degeneration.