A multifunctional dendrimer nanoparticle and method of treating diseases of the posterior segment of the eye is presented. The functionalized polyamidoamine (PAMAM) dendrimer effectively delivers drugs and/or genes to the posterior eye, thereby providing for the effective, non-invasive, and topical treatment of diseased in the posterior eye. The multifunctional dendrimer nanoparticle has shRNA-encoding DNA and small molecule drug encapsulated cyclodextrin complexed to the outer surface of the dendrimer for delivery to the posterior segment of the eye.