Purpose: The purpose of this study was to investigate the association between autonomic nerve activity and symptom intensity according to the type of dry eye (DE).
Methods: This prospective, cross-sectional, comparative study included 25 eyes of 25 patients with short tear break-up time DE (sBUTDE; mean age = 57.4 ± 11.4 years, range = 30-74 years) and 24 eyes of 24 patients with aqueous tear-deficient DE (ADDE; mean age = 62.3 ± 10.7 years, range = 29-76 years) were studied. Autonomic nerve activity was examined, and the Japanese version of the Ocular Surface Disease Index (J-OSDI) and a stress check questionnaire were administered. Autonomic nerve activity was continuously measured for 10 minutes. The parameters were low-frequency (LF) and high-frequency (HF) components of heart rate variability, reflecting cardiac sympathetic and parasympathetic nerve activity, and parasympathetic nerve activity alone, respectively; and the coefficient of variation of R wave-to-R wave (RR) interval (cvRR), component coefficient of variation of LF (ccvLF), and component coefficient of variation of HF (ccvHF), reflecting fluctuation of RR interval, LF, and HF, respectively.
Results: Higher J-OSDI scores were associated with higher HF, ccvHF, and subjective stress in sBUTDE, showing a significant correlation (r = 0.53, P < 0.01; r = 0.55, P = 0.01; and r = -0.66, P = 0.01); no correlations were observed between the J-OSDI score and autonomic parameters and stress in ADDE.
Conclusions: DE symptoms were significantly associated with the magnitude and fluctuation of parasympathetic activity in sBUTDE. Thus, among the autonomic parameters, parasympathetic activity is involved in the development of symptoms in sBUTDE, whereas the involvement of the autonomic nervous system may be minimal in ADDE.