Department of Mechatronics, Optics and Mechanical Engineering Informatics, Budapest University of Technology and Economics, Budapest, Hungary.
Department of Ophthalmology, Semmelweis University, Budapest, Hungary.
Doc Ophthalmol. 2022 Jun;144(3):191-202. doi: 10.1007/s10633-021-09853-9. Epub 2021 Sep 24.
Human oscillatory potentials (OPs) are derived from dark-adapted (DA) electroretinograms (ERGs) with fixed frequency cutoff filters while light-adapted (LA) OPs are generally not isolated from ERGs. Our purpose was to analyze the effect of cutoff frequencies on DA and LA ERG components using a series of fixed and variable filters.
DA and LA ERGs were recorded from 10 healthy eyes of 10 subjects (mean age = 20.5 ± 6.7 years) following ISCEV standards. Each signal was filtered in the Fourier domain to acquire slow (a- and b-waves; below cutoff frequency) and fast (OPs; above cutoff frequency) components. Fixed cutoff frequencies ranged from 60 to 105 Hz and a variable cutoff frequency was calculated. Results were analyzed with statistical tests and specific models.
DA ERG components were slightly influenced by the filter cutoff frequency. In contrast, fixed and variable filters significantly changed LA components: the lower the cutoff frequency the smaller the b-wave and OP3 and the higher the OP2/OP4 amplitudes. Analyzing the filter frequency limits a transition range between 68.9 Hz and 83.9 Hz was observed where amplitudes vary.
The present report shows that DA OPs may be isolated from ERGs using filtering procedures with high-pass cutoff frequency at about 75 Hz as recommended by ISCEV. On the other hand, the spectral distribution of low-frequency and high-frequency LA ERG components may overlap. Accordingly, filtering the signal using different cutoff frequencies is not necessarily separating b-wave and OPs.
人体振荡电位（OPs）是从暗适应（DA）视网膜电流图（ERGs）中通过固定频率截止滤波器得出的，而光适应（LA）OPs 通常不能从 ERGs 中分离出来。我们的目的是使用一系列固定和可变滤波器来分析截止频率对 DA 和 LA ERG 成分的影响。
按照 ISCEV 标准，对 10 名受试者（平均年龄 20.5±6.7 岁）的 10 只健康眼睛进行 DA 和 LA ERG 记录。每个信号都在傅里叶域中进行滤波，以获取慢（a-和 b-波；低于截止频率）和快（OPs；高于截止频率）成分。固定截止频率范围从 60 到 105 Hz，并且计算了一个可变截止频率。使用统计检验和特定模型分析结果。
DA ERG 成分受滤波器截止频率的影响较小。相比之下，固定和可变滤波器显著改变了 LA 成分：截止频率越低，b 波和 OP3 越小，OP2/OP4 幅度越高。分析滤波器频率限制表明，在 68.9 Hz 和 83.9 Hz 之间存在一个幅度变化的过渡范围。
本报告表明，DA OPs 可以使用 ISCEV 推荐的约 75 Hz 的高通截止频率滤波程序从 ERGs 中分离出来。另一方面，低频和高频 LA ERG 成分的光谱分布可能重叠。因此，使用不同的截止频率滤波信号不一定能分离 b 波和 OPs。
