[Effective mechanisms of laser photocoagulation for neovascularization in diabetic retinopathy]

Effective mechanisms of laser photocoagulation for neovascularization in diabetic retinopathy were investigated in regard to change in oxygen pressure in the retina and vitreous and cytokines related to ischemia. The mechanism of laser photocoagulation is suggested to be as follows. 1. Destruction of the outer retina, especially of photoreceptors that have high oxygen consumption decreases metabolic function of the outer retina and its oxygen consumption. 2. The destruction allows increase of oxygen diffusion from choroidal vessels to inner retina, which improves the metabolic function by equilibrating oxygen demand and supply in the inner retina. (3) Production and secretion of neovascular factors such as vascular endothelial growth factor (VEGF) is decreased by the improvement of hypoxia. 4. The neovascularization is decreased by the synergistic effect between the neovascular factors and suppressors such an VEGF, fibroblast growth factor (FGF), and transforming growth factor-beta (TGF-beta). The improvement of the retinal ischemia and the decrease of cytokines are implicated in the regression of neovascularization by the laser photocoagulation for diabetic retinopathy.