To date aptamers, recombinant antibodies and antibody fragments which interfere specifically in cellular signal transmission by binding transmitters before a signal can be triggered, are the approved therapeutics agents for treatment of ocular angiogenesis. These substances achieve an effective but in most cases temporary inhibition of vascular growth and permeability. Other alternatives to inhibit cellular communication, such as tyrosine kinase inhibition or especially post-transcriptional gene silencing by degradation of messenger RNA (mRNA) induced by small interfering RNA (siRNA) are being evaluated in ongoing studies. In this overview issues related to mechanisms and molecule design, as well as clinical applications and the first clinical experience in ophthalmology reported on siRNA will be discussed.