Neovascularization is the formation of functional microvascular networks with re blood cell perfusion. Neovascularization differs from angiogenesis in that angiogenesis is mainly characterized by the protrusion and outgrowth of capillary buds and sprouts from pre-existing blood vessels. In ophthalmology, choroidal neovascularization is the formation of a microvasculature within the innermost layer of the choroid of the eye.