Correlation between ERG and morphometric parameters of optic nerve head and nerve fiber layer

目的：探讨青光眼局灶性视网膜电图(ERG)的明视负波反应(PhNR)与视网膜内层及视神经头结构参数的关系。方法：对61例(61眼)开角型青光眼患者、13例(13眼)可疑青光眼患者和30例(30眼)正常人进行研究。以中心凹为中心的白色背景，15°圆形白色刺激，可诱发出焦点ERG。放置在黄斑上方或下方的半个环也可引起局灶性ERG。环带内缘直径15°，外缘直径30°。分别用扫描激光眼镜法和激光扫描偏振仪测量视神经头结构和视网膜神经纤维层厚度(RNFLT)。结果：在上/颞区和下/颞区，焦点PhNRs的波幅和PhNR/b波波幅的比值与相应的RNFLT呈线性相关(r=0.0001.43~0.47；P<0.0 5)，而在颞区与相应的RNFL无相关性。病灶PhNR波幅和PhNR/b波波幅比值与相应的边缘面积和杯盘面积比也呈线性相关(r=0.0001.38~0.5 0，P<0.0 5)。结论：视网膜或视神经头局部区域视网膜神经元的解剖缺失是OAG局灶性PhNR波幅降低的原因之一。

Purpose : To determine the relationship between the photopic negative response (PhNR) of the focal electoretinogram (ERG) and the structural parameters of the inner retina and optic nerve head in glaucoma. Methods : Sixty-one eyes of 61 patients with open angle glaucoma (OAG), 13 eyes of 13 patients who were classified as glaucoma suspects, and 30 eyes of 30 normal subjects were studied. The focal ERGs were elicited by a 15° circular white stimulus on a white background centered on the fovea. The focal ERGs were also elicited by half of an annulus placed above or below the macula. The diameter of the inner border of the annulus was 15° and that of the outer border was 30°. The structure of the optic nerve head and retinal nerve fiber layer thickness (RNFLT) were evaluated by scanning laser ophthalmocopy and laser scanning polarimetry, respectively. Results : The amplitudes of the focal PhNRs and the ratio of the focal PhNR/b-wave amplitude were linearly correlated with the corresponding RNFLT in the superior/temporal and inferior/temporal regions (r=0.43 to 0.47 ; P<0.0001) but not in the temporal region. The focal PhNR amplitude and focal PhNR/b-wave amplitude ratio were also linearly and significantly correlated with the corresponding rim areas and cup/disc area ratio (r=0.38 to 0.50, P<0.0001). Conclusions : These results strongly suggest that the anatomical losses of retinal neurons in local areas of the retina or optic nerve head are a cause of the reduction in the amplitude of the focal PhNR in OAG..