Study on the Correlation between OBF and Age Based on Analysis of Time Domain and Frequency Domain

Abstract Many studies indicate that the old people are prone to high blood pressure with the age growing. Elevated blood pressure can lead to the changes of hemodynamic parameters in the blood circulation system, and then cause abnormal changes in the physiological activities of the endothelium, heart and so on. These Characteristic of physiological rhythm reflect the changes of ocular blood pressure and ocular blood flow signals. Thus, we could study on the correlation between ocular blood flow (OBF) and age by analyzing the variety of age on hemodynamic. The paper sets out to fully examine the time domain and frequency domain relationship between OBF and age. Time domain: the paper introduces the thigh cuff method to produce sudden drops in arterial blood pressure (ABP) and study the evolution of the immediate OBF response with LSFG. The LSFG (Laser Speckle Flow graph) allows for quantitative estimation of blood flow in the optic nerve head (ONH), and it is the only noninvasive method that allows sufficient temporal resolution to measure these rapid changes. The paper studies on the relationship between time-domain parameter Kr(L) (The slope of DAR descending curve), Kr(R) (The slope of DAR up curve), Tr(L) (The amount of time it takes to the maximal BF or BP decrease), Tr(R) (The amount of time it takes to the maximal BF or BP increase) and age, respectively. Kr(R), Kr(R), Tr(R) are shown significantly influenced by age changing. Frequency domain: in the case of without any factor, the harmonic content of the envelope waveform of the blood flow velocity in the ophthalmic artery is analyzed in aging and OBF. Cronbach-α reliabilities of the calculated frequency coefficient (FC) and frequency index (FI) are 0.91 and 0.92, respectively. The FI of the ophthalmic artery allows an assessment of the ocular circulation in consideration of age and OBF. The order the age, the smaller the FC, FI in OBF.