Matsui Y, Katsumi O, Sakaue H, Hirose T
Schepens Eye Research Institute, Boston.
Br J Ophthalmol. 1994 Mar;78(3):191-8. doi: 10.1136/bjo.78.3.191.
The electroretinogram (ERG), especially the b/a wave ratio, is considered a good indicator of retinal ischaemia in central retinal vein obstruction (CRVO). Seven CRVO patients who showed b/a wave ratio improvement from < 1.0 [negative type (-) ERG] to > or = 1.0 and one from 1.07 to 1.53 were studied. Three mechanisms of change were observed: firstly, the b-wave amplitude increased without an a-wave amplitude decrease (group A, n = 2); secondly, the b-wave amplitude increased with an a-wave amplitude decrease (group B, n = 4); and, thirdly, both decreased, but the a-wave amplitude decreased more markedly (group C, n = 2). In group A, the visual acuities improved markedly. In group B, the visual acuities improved in two cases in which the b-wave amplitude reached the normal range; the visual acuities did not improve in two cases in which the b-wave amplitude did not reach the normal range. In group C, the visual acuities remained poor. The negative (-) ERG or significantly reduced b/a wave ratio is associated with ischaemic CRVO and did not occur because of the filtering effect of the haemorrhage, which may reduce the stimulus light for the ERG. Improvement of the reduced b/a wave ratio with an increased b-wave amplitude was accompanied by improvements in fundus appearance and visual acuity in CRVO. The results suggest that the retinal ischaemia in CRVO, as revealed by the ERG and fluorescein angiogram, may be reversible in some cases.
视网膜电图（ERG），尤其是b/a波比值，被认为是视网膜中央静脉阻塞（CRVO）中视网膜缺血的良好指标。对7例CRVO患者进行了研究，这些患者的b/a波比值从<1.0（负型（-）ERG）改善至>或 = 1.0，还有1例从1.07改善至1.53。观察到三种变化机制：首先，b波振幅增加而a波振幅未降低（A组，n = 2）；其次，b波振幅增加且a波振幅降低（B组，n = 4）；第三，两者均降低，但a波振幅降低更明显（C组，n = 2）。在A组中，视力明显改善。在B组中，b波振幅达到正常范围的2例患者视力改善；b波振幅未达到正常范围的2例患者视力未改善。在C组中，视力仍然很差。负（-）ERG或显著降低的b/a波比值与缺血性CRVO相关，并非由于出血的滤过效应导致，出血可能会减少ERG的刺激光。CRVO中b/a波比值降低且b波振幅增加的改善伴随着眼底外观和视力的改善。结果表明，ERG和荧光素血管造影显示的CRVO中的视网膜缺血在某些情况下可能是可逆的。
