Experimental rat model of neovascularization arising from the optic disk.

A consistent animal model of intraocular neovascularization was developed in the rat. A vitreous hemorrhage was induced by an experimental incision through the pars plana in the right eye of 24 rats. One month after the incision, 21 eyes produced a definite posthemorrhagic neovascularization arising from the optic disk. Histologically, the newly formed vessels consisted of endothelial cells forming lumina and surrounding smooth muscle cells. The proliferating activity of these cells was confirmed by immunohistochemical staining for proliferating cell nuclear antigen. An electron-microscopic examination also revealed mitotic activity and the cytoplasmic budding of immature endothelial cells. The 24 left eyes served as controls and showed no evidence of neovascularization.