Autonomic nerve activity in dry eye with decreased tear stability

Abstract Stress might activate sympathetic nerve activity, causing dry eye (DE). We investigated biological parameters reflecting autonomic nerve activity in DEs with decreased tear stability. This prospective, cross-sectional, comparative study enrolled 34 eyes of 34 participants (mean age: 52.5 ± 13.4 years; range: 20–81 years) without keratoconjunctival damage. The 19 eyes in the DE group showed DE symptoms and tear break-up time (BUT) ≤ 5 seconds (short BUT DE); the 15 eyes in the non-DE group showed no DE symptoms. Autonomic nerve activity was measured for 10 minutes—starting and ending 5 minutes before and after instilling ophthalmic solution—and evaluated using the low-frequency component (LF) to the high-frequency component (HF) ratio of heart rate variability (autonomic balance). The pre-instillation LF/HF ratio was not significantly different (P = 0.86). The pre-instillation standard deviation of the LF/HF ratio (LF/HF-SD) was higher in the DE group than in the non-DE group (P = 0.05). DE symptoms intensity was significantly related to LF/HF-SD (P = 0.005). The LF/HF-SD significantly decreased post-instillation in the DE group (P = 0.03). The large fluctuations observed in the autonomic balance were related to DE symptom intensity in short BUT DE and may improve understanding of the DE-symptom mechanism.