Proliferative neovascular retinopathies may be caused by the release of a hypothetical vasoproliferative factor, but mechanical factors seem to self-perpetuate the disease as well. Contraction of proliferative tissue causes vitreous detachment and traction on the retina. Congestion of vascular fronds by traction further stimulates vascularization. Traction on vessels results in hemorrhages. Surgical removal of all intravitreal scaffolds by vitrectomy seems to eliminate the development of this vicious cycle. Results of vitreous surgery seem to indicate that the hypothesis of scaffold removal is valid.