Autonomic Dysfunction in Normal Tension Glaucoma: The Short-term Heart Rate Variability Analysis

Abstract

The purpose of this study was to investigate the dysfunction of autonomic control that may be a contributing factor in normal tension glaucoma (NTG) by showing the short-term heart rate variability in NTG patients. Newly diagnosed NTG patients and an age-matched normal control group were enrolled in this prospective study. Blood pressure was obtained and the electrocardiogram was monitored for 5 minutes after 30-minute rest in a supine position. Electrocardiographic signals were transferred to a heart rate analyzer. The time and frequency domain parameters of heart rate variability were analyzed between two groups. In all, 77 NTG patients and 30 healthy controls were included in the study. There were no significant differences between NTG and controls with respect to age, sex, and a hypertensive history, heart rate, systolic pressure, and diastolic pressure. NTG patients showed a significant reduction in the standard deviation of the mean of qualified normal-to-normal intervals in comparison with controls (27.64+/-10.90 vs. 36.22+/-10.21, P=0.041). Low-frequency values in NTG patients were statistically lower than in healthy controls (P=0.001) and the low-frequency/high-frequency ratio was significantly higher in the NTG group (P=0.000). Our study results showed that the dysfunction of an autonomic control is associated with NTG patients.