Autonomic nervous system and endothelial peripheral dysfunction in normal tension glaucoma patients

Abstract

Abstract Purpose To define parameters of autonomic nervous system activity and peripheral vascular reactive hyperemia in normal tension glaucoma patients. Methods Ambulatory 24‐hour electrocardiogram and blood pressure (BP) monitoring by using Lifecard CF and SpaceLab 90207‐30 combined with occlusion provocation test were carried out in 54 NTG patients (44 women, mean age 59.7) and 43 matched control subjects (34 women, mean age 57.0). Heart rate variability (HRV) time and frequency domain parameters [low‐frequency (LF), high‐frequency (HR) and LF/HF ratio], and blood pressure variability (BPV) were calculated and analyzed for both study groups. Postocclusive hyperemia response parameters (TM ‐ time to peak flow, TH –half‐time hyperaemia, TR –time to rest flow, BZ‐biological zero and MAX – maximum hyperemic response) were compared for patients with a nocturnal fall in mean BP (MPB) of less than 10% (non‐dippers), of 10‐20% (dippers) and of more than 20% (over‐dippers) Results NTG patients demonstrated higher LF and LF/HF values for 24‐hour period, day‐time and night time than control subjects. There was no difference in BPV between study groups (10.4 ± 1.9 vs. 10.5 ± 2.1, p=0.790). In NTG patients, TH was significantly higher (79.0 ± 80.9 s vs. 51.5 ± 35.3 s, p=0.028) and BZ was significantly lower (2.3 ± 1.0 vs. 3.1 ± 2.0, p=0.009) as compared to the control group. There was statistically significant difference between NTG non‐dippers, dippers and over–dippers in the BZ parameter (2.3 ± 0.9 vs. 2.7 ± 1.3 vs. 1.4 ± 0.4 p=0.024). Conclusion NTG patients exhibit abnormal ANS system activity and a different systemic hyperemia response as compared with healthy subjects.