Braun R D, Linsenmeier R A
Department of Chemical Engineering, Northwestern University, Evanston, Illinois 60208.
Invest Ophthalmol Vis Sci. 1995 Mar;36(3):523-41.
Retinal oxygen tension (PO2), photoreceptor oxygen consumption (QO2), the local electroretinogram (LERG), and the vitreally recorded electroretinogram (ERG) were evaluated during retinal artery occlusion in the cat. The feasibility of supplying the retina with oxygen during occlusion by ventilation with 100% O2 was evaluated.
Double-barreled oxygen microelectrodes were used to measure intraretinal PO2 and LERGs in anesthetized cats before, during, and after occlusion of a single retinal artery. Outer retinal (photoreceptor) QO2 was determined from retinal PO2 profiles.
During air breathing, occlusion obliterated the LERG b-wave and reduced the vitreal ERG by the amount expected from the area supplied by the occluded vessel. The PO2 in the entire inner retina was zero, and photoreceptor QO2 was decreased by approximately 25%. Inspiration of 100% O2 restored the b-wave amplitude to approximately 50% of normal and increased the amount of O2 reaching the inner retina. Hyperoxia could not guarantee nonzero PO2 across the entire retina in either darkness or light, but it elevated the average PO2 in the innermost 25% of the retina to more than 20 mm Hg. The b-wave amplitude must have been affected by some factor in addition to local hypoxia, because the amplitude was not correlated with inner retinal PO2 during occlusion, and a normal PO2 did not result in a normal LERG. Effects of 2 to 2.5 hours of occlusion were reversible if 100% O2 inspiration was maintained during most of the occlusion.
Ventilation with 100% O2 during occlusion increased the PO2 across most of the retina and partially restored the LERG b-wave, but the tissue near the vitreous was still sometimes anoxic. The illumination status seemed to make little difference. Inspiration of elevated O2 might be beneficial in treating retinal vascular occlusive disease, although it alone cannot completely maintain retinal function.
在猫视网膜动脉阻塞期间，评估视网膜氧张力（PO₂）、光感受器氧消耗（QO₂）、局部视网膜电图（LERG）以及经玻璃体记录的视网膜电图（ERG）。评估在阻塞期间通过100%氧气通气为视网膜供氧的可行性。
使用双管氧微电极在麻醉猫的单条视网膜动脉阻塞前、阻塞期间和阻塞后测量视网膜内PO₂和LERG。根据视网膜PO₂曲线确定外层视网膜（光感受器）QO₂。
在空气呼吸期间，阻塞使LERG的b波消失，并使经玻璃体ERG降低，降低幅度与阻塞血管所供应区域预期的幅度一致。整个内层视网膜的PO₂为零，光感受器QO₂降低约25%。吸入100%氧气可使b波振幅恢复至正常的约50%，并增加到达内层视网膜的氧气量。无论在黑暗还是光照条件下，高氧都无法保证整个视网膜的PO₂非零，但它将视网膜最内层25%的平均PO₂提高到超过20 mmHg。b波振幅除了受局部缺氧影响外，肯定还受其他因素影响，因为在阻塞期间振幅与内层视网膜PO₂不相关，且正常的PO₂并未导致正常的LERG。如果在大部分阻塞期间维持100%氧气吸入，2至2.5小时阻塞的影响是可逆的。
阻塞期间用100%氧气通气可增加大部分视网膜的PO₂，并部分恢复LERG的b波，但玻璃体附近的组织有时仍处于缺氧状态。光照状态似乎影响不大。吸入高浓度氧气可能对治疗视网膜血管阻塞性疾病有益，尽管仅靠它不能完全维持视网膜功能。
