Tomic Lidija, Bjärnhall Gunilla, Mäepea Olav, Sperber Göran O, Alm Albert
Department of Neuroscience, Ophthalmology, Uppsala University, Uppsala, Sweden.
Acta Ophthalmol Scand. 2005 Dec;83(6):705-10. doi: 10.1111/j.1600-0420.2005.00522.x.
To investigate the quantitative response of retinal circulation in normal human eyes to oxygen and carbon dioxide provocation and to gain more information about retinal mean transit time (MTT).
Healthy subjects were studied while breathing: room air (O(2) baseline); pure O(2); room air (CO(2) baseline), and CO(2) in room air. The CO(2) level was brought to 30% above individual baseline level. During each gas exposure, blue field simulation was used to estimate the velocity of macular leucocytes and fluorescein angiography was used to determine MTT, arteriovenous passage time (AVP) and vessel diameters.
Breathing pure O(2) caused a reduction in macular leucocyte velocity of about 13%, a non-significant change in MTT and AVP from baseline, and a 10% reduction in the diameter of temporal retinal arteries and veins. Breathing CO(2) caused an increase in macular leucocyte velocity of 21%, a non-significant change in MTT and AVP, and no change in retinal vascular diameters.
Both O(2) and CO(2) had the expected effects on retinal blood flow, as judged by leucocyte velocity in the macular capillaries, but little effect on retinal MTT, indicating concomitant changes in flow and retinal vascular volume. Measuring the diameter of retinal vessels before and during pure O(2) breathing is a simple and effective way of determining the reactivity of retinal vessels.
研究正常人类眼睛视网膜循环对氧气和二氧化碳激发的定量反应，并获取更多关于视网膜平均通过时间（MTT）的信息。
对健康受试者在呼吸以下气体时进行研究：室内空气（氧气基线）；纯氧；室内空气（二氧化碳基线），以及含二氧化碳的室内空气。将二氧化碳水平提高到个体基线水平以上30%。在每次气体暴露期间，使用蓝场模拟来估计黄斑区白细胞的速度，并使用荧光素血管造影来确定MTT、动静脉通过时间（AVP）和血管直径。
呼吸纯氧导致黄斑区白细胞速度降低约13%，MTT和AVP与基线相比无显著变化，颞侧视网膜动脉和静脉直径减少10%。呼吸二氧化碳导致黄斑区白细胞速度增加21%，MTT和AVP无显著变化，视网膜血管直径无变化。
从黄斑区毛细血管白细胞速度判断，氧气和二氧化碳对视网膜血流均有预期影响，但对视网膜MTT影响较小，表明血流和视网膜血管容积存在伴随变化。在呼吸纯氧之前和期间测量视网膜血管直径是确定视网膜血管反应性的一种简单有效的方法。
