Nair Surya S, Joseph K Paul
Electrical Engineering Department, National Institute of Technology, Calicut, Kerala 673601, India.
Biomed Res Int. 2014;2014:503920. doi: 10.1155/2014/503920. Epub 2014 Jun 15.
Electroretinogram (ERG) is a time-varying potential which arises from different layers of retina. To be specific, all the physiological signals may contain some useful information which is not visible to our naked eye. However this subtle information is difficult to monitor directly. Therefore the ERG signal features which are extracted and analyzed using computers are highly useful for diagnosis. This work discusses the chaotic aspect of the ERG signal for the controls, congenital stationary night blindness (CSNB), and cone-rod dystrophy (CRD) classes. In this work, nonlinear parameters like Hurst exponent (HE), the largest Lyapunov exponent (LLE), Higuchi's fractal dimension (HFD), and approximate entropy (ApEn) are analyzed for the three different classes. It is found that the measures like HE dimension and ApEn are higher for controls as compared to the other two classes. But LLE shows no distinguishable variation for the three cases. We have also analyzed the recurrence plots and phase-space plots which shows a drastic variation among the three groups. The results obtained show that the ERG signal is highly complex for the control groups and less complex for the abnormal classes with P value less than 0.05.
视网膜电图（ERG）是一种源自视网膜不同层次的随时间变化的电位。具体而言，所有生理信号可能都包含一些我们肉眼无法察觉的有用信息。然而，这些细微信息很难直接监测到。因此，利用计算机提取和分析的ERG信号特征对诊断非常有用。这项工作探讨了对照组、先天性静止性夜盲（CSNB）和锥杆营养不良（CRD）类别的ERG信号的混沌特性。在这项工作中，对这三种不同类别分析了诸如赫斯特指数（HE）、最大李雅普诺夫指数（LLE）、 Higuchi分形维数（HFD）和近似熵（ApEn）等非线性参数。结果发现，与其他两类相比，对照组的HE维数和ApEn等指标更高。但LLE在这三种情况下没有明显差异。我们还分析了递归图和相空间图，结果显示这三组之间存在显著差异。所得结果表明，对照组的ERG信号高度复杂，而异常类别的信号复杂度较低，P值小于0.05。
