Neovascularization

(Medicine) abnormal formation of blood vessels; restoration of blood supply to a body part

Neovascularization is the formation of functional microvascular networks with red 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.
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the growth of new, small blood vessels. In the retina, this may lead to loss of vision or blindness.
  

growth of new, fragile blood vessels which may leak beneath the retina.