Alder V A, Cringle S J
Lions Eye Institute, University of Western Australia, Nedlands.
Graefes Arch Clin Exp Ophthalmol. 1990;228(2):151-7. doi: 10.1007/BF00935725.
This paper reports the results of experiments carried out to understand the oxygenation of the normal retina in response to alterations in physiological conditions such as inspired oxygen concentration, elevated IOP, luminance changes and occlusion of the retinal circulation. Measurements of vitreal and intraretinal PO2 in vivo in the cat using oxygen-sensitive microelectrodes demonstrated that large PO2 gradients were set up preretinally and that arterial, venous and tissue PO2 increased when inspired PO2 was raised to 100% O2. Results showed that with an occluded retinal circulation, it was possible to oxygenate fully the whole retina with oxygen supplied from a hyperoxic choroidal circulation. With alterations in background luminance from photopic to scotopic, preretinal PO2 was unaffected for air breathing, whereas for 100% O2, breathing vitreal PO2 fell quickly and reversibly on a switch from photopic to scotopic conditions, reflecting an increase in retinal oxygen consumption in a dark environment. During acute rises of IOP, the PO2 at the choriocapillaris fell and an anoxic region developed in the middle retinal layers. The inner retina was relatively resistant to rises in IOP. The implications of these data for autoregulation of the retinal circulation are discussed.
本文报告了一系列实验结果，这些实验旨在了解正常视网膜在诸如吸入氧浓度、眼压升高、亮度变化和视网膜循环阻塞等生理条件改变时的氧合情况。使用氧敏感微电极在猫体内对玻璃体和视网膜内的PO2进行测量，结果表明视网膜前会形成较大的PO2梯度，并且当吸入PO2升至100% O2时，动脉、静脉和组织的PO2会增加。结果显示，在视网膜循环阻塞的情况下，利用来自高氧脉络膜循环的氧气可以使整个视网膜充分氧合。随着背景亮度从明视觉变为暗视觉，对于空气呼吸，视网膜前PO2不受影响，而对于100% O2呼吸，从明视觉切换到暗视觉条件时，玻璃体PO2会迅速且可逆地下降，这反映了在黑暗环境中视网膜氧消耗的增加。在眼压急性升高期间，脉络膜毛细血管处的PO2下降，视网膜中层出现缺氧区域。视网膜内层对眼压升高相对具有抗性。本文还讨论了这些数据对视网膜循环自动调节的意义。
