The Wikipedia page for vascular endothelial growth factor (VEGF) looks pretty useful - it explains that VEGF stimulates the growth of blood vessels. If this gets out of balance, for example in diabetic retinopathy and wet form age-related macular degeneration, one treatment is to attempt to reduce levels of VEGF in the circulation, using monoclonal antibodies directed against VEGF, or to antagonise the action of VEGF using drugs that target the VEGF receptors.
Two milestones in anti-VEGF therapy are described in these papers:
Ng et al. (2006) Pegaptanib, a targeted anti-VEGF aptamer for ocular vascular disease. Nature Reviews Drug Discovery 5: 123-132 (This paper describes the first approved aptamer drug: an RNA directed against VEGF.)
Ferrara et al. (2006) Development of ranibizumab, an anti-vascular endothelial growth factor antigen binding fragment, as therapy for neovascular age-related macular degeneration. Retina 26:859-870 (This paper describes a therapy based upon an antibody fragment directed at all isoforms of VEGF-A.)
A very recent review of anti-VEGF therapies is:
Freund et al. (2013) An update on the pharmacotherapy of neovascular age-related macular degeneration. Expert Opinion on Pharmacotherapy 14:1017-1028