Altered autonomic balance in normal tension glaucoma

Abstract

Objective: To study autonomic imbalance if any in normal tension glaucoma (NTG)patients by heart rate variability (HRV)and head-up tilt (HUT)test. Methods: The study subjects of age between 45 and 65 years of either sex comprised 20 patients with NTG (Group ІІ)and 20 age- and sex-matched healthy controls (Group І). Different variables of time and frequency domain of HRV were analyzed at rest, during HUT and the recovery period. Results: Highly significant decrease in value of root mean square successive difference observed in Group ІІ (p<0.000)in comparison to controls. The high-frequency variables (HF [nu]and HF [ms2])were significantly less (p<0.000)and low frequency (LF)/HF ratio was significantly high (p<0.000) in Group ІІ. Conclusion: During stress test, i.e., HUT there was the greater withdrawal of parasympathetic input to heart; hence, there was relatively over sympathetic activity due to sympatho-vagal imbalance.