Pournaras C J
Department of Clinical Neurosciences, University of Geneva, Switzerland.
Retina. 1995;15(4):332-47.
To study the role of oxygen distribution in the physiopathology of retinal vasoproliferative microangiopathies.
Experimental retinal branch vein occlusion was induced in miniature pigs, using argon laser photocoagulation. The microvascular modifications, the retinal histologic features, and the retinal oxygen distribution were studied within 48 hours of the occlusion, and 3 weeks later. The retinal oxygen distribution modifications were also studied in ischemic retinal areas treated by scatter argon laser photocoagulation.
Impaired regulation and blood flow decrease in the vascular bed that was affected by a retinal branch vein occlusion and tissue hypoxia led to modifications of oxygen delivery resulted in a damage of the neuronal cells, whereas the abnormal permeability of the affected retinal vessel wall induced extracellular edema and disorganization of the inner retina. Three weeks after vein occlusion, retinal neovascularization occurred in ischemic/hypoxic retinas. The "critical PO2" (tissue oxygen partial pressure), which induces neovascularization in miniature pigs has not been determined. Photocoagulation of the ischemic retinal territories induced an increase of preretinal oxygen partial pressure, which is restored to the normal preretinal values.
A retinal branch vein occlusion in miniature pigs represents a reproducible experimental model of retinal neovascularization. Oxygen partial pressure measurements of the ischemic retina confirmed the hypothesis that tissue hypoxia triggers neovascularization; laser photocoagulation should be applied over the whole ischemic retinal areas to eliminate hypoxia in the inner retina.
研究氧分布在视网膜血管增生性微血管病变病理生理学中的作用。
使用氩激光光凝术诱导小型猪发生实验性视网膜分支静脉阻塞。在阻塞后48小时内及3周后，研究微血管改变、视网膜组织学特征和视网膜氧分布。还对经散在氩激光光凝术治疗的缺血性视网膜区域的视网膜氧分布改变进行了研究。
受视网膜分支静脉阻塞影响的血管床调节受损和血流减少以及组织缺氧导致氧输送改变，进而导致神经元细胞受损，而受影响的视网膜血管壁异常通透性引起细胞外水肿和视网膜内层结构紊乱。静脉阻塞3周后，缺血/缺氧视网膜发生视网膜新生血管形成。尚未确定在小型猪中诱导新生血管形成的“临界PO₂”（组织氧分压）。缺血性视网膜区域的光凝术导致视网膜前氧分压升高，其恢复到正常视网膜前值。
小型猪的视网膜分支静脉阻塞代表了一种可重复的视网膜新生血管形成实验模型。缺血性视网膜的氧分压测量证实了组织缺氧触发新生血管形成的假设；应在整个缺血性视网膜区域应用激光光凝术以消除视网膜内层的缺氧。
