Abstract
Purpose: :
To evaluate the activity and characteristics of the central autonomic nervous system (ANS), peripheral vascular system and retrobulbar circulation in normal tension glaucoma (NTG) patients.
Methods: :
Ambulatory automated 24-hour electrocardiogram (Lifecard CF) and blood pressure (BP) monitoring (SpaceLab 90207-30) combined with occlusion provocation test (laser-Doppler flowmeter MBF-3d) and color Doppler imaging of retrobulbar vessels (LOGIQ 7 CDI System) were carried out in 54 NTG patients (44 women, mean age 59.7) and 43 control subjects (34 women, mean age 57.0).Heart rate variability time and frequency domain parameters [low-frequency (LF), high-frequency (HR) and LF/HF ratio], and blood pressure variability (BPV) were determined. 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 blood pressure (MPB) of less than 10% (non-dippers), of 10-20% (dippers) and of more than 20% (over-dippers). For the ophthalmic (OA), central retinal (CRA) and short posterior ciliary arteries (temporal and nasal) (TSPCA, NSPCA) the peak systolic (PSV), end diastolic (EDV) velocities and resistance index (RI) were estimated.
Results: :
For 24-hour period, day-time and night-time, NTG patients demonstrated higher LF (62.6 vs. 55.8 p=0.0048, 64.3 vs. 59.9 p=0.0431 and 59.7 vs. 47.6 p=0.0000) and LF/HF values (3.2 vs. 2.2 p=0.0009, 3.5 vs. 2.7 p=0.0173 and 2.6 vs.1.4 p=0.0001) than control subjects. There was no difference in BPV between study groups (10.4 vs.10.5 p=0.790). In NTG patients, TH was higher (79.0 vs. 51.5, p=0.028) and BZ was lower (2.3 vs. 3.1 p=0.009) as compared to the controls. There was statistically significant difference between non-dippers, dippers and over-dippers in the BZ parameter. In NTG patients, the CRA PSV, CRA EDV and TSPCA EDV were significantly lower and the CRA RI was significantly higher as compared to the controls.
Conclusions: :
NTG patients exhibied shifting of the balance of ANS towards the sympathetic nervous system dominance, abnormal peripheral hyperemia response and disturbed retrobulbar hemodynamics compared with healthy subjects.
Keywords: blood supply • imaging/image analysis: clinical • optic flow