Arterial stiffness shown by the cardio-ankle vascular index is an important contributor to optic nerve head microcirculation

PROPOSE: The purpose of this study was to determine whether there were significant correlations between the pulse waveform in the capillary area of the optic nerve head (ONH) microcirculation shown by laser speckle flowgraphy (LSFG) and parameters of the systemic condition, especially the cardio-ankle vascular index (CAVI). METHOD: We studied 130 men (ages 60.5 ± 10.9 years) who visited the Vascular Function Section of the Department of Cardiovascular Center of Toho University Sakura Medical Center. We evaluated the skew and blowout time (BOT) — which are parameters of pulse waveform analyses — using LSFG in the capillary area of the ONH for each patient. The CAVI, the E/e’ ratio as the measure of diastolic left ventricular function, and the mean intima-media thickness (IMT) were evaluated as systemic parameters. We performed a Pearson’s correlation analysis and a multiple regression analysis to determine independent factors for skew and BOT. RESULTS: Heart rate, spherical refraction, and the CAVI (standard regression = 0.18, t = 2.61, p = 0.01) were revealed as factors contributing independently to the skew by multiple regression analysis. Heart rate, the CAVI (standard regression = −0.27, t = −3.92, p = 0.0002), the urinary albumin concentration, the mean IMT, spherical refraction, body mass index and pulse pressure were revealed as factors contributing independently to the BOT by multiple regression analysis. CONCLUSION: The CAVI was demonstrated to be an independent factor contributing to both skew and BOT in the capillary area of the ONH. Our findings clarified that large arterial function shown by the CAVI contributes to smooth hemodynamics of microcirculation, shown by LSFG.