Autonomic Nerve Activity Features According to Dry Eye Type

Area of Science:

• Ophthalmology
• Autonomic Neuroscience
• Medical Physiology

Background:

• Dry eye (DE) is a prevalent ocular condition with diverse etiologies.
• Understanding the role of the autonomic nervous system (ANS) in DE symptomology is crucial for targeted treatment.
• Distinguishing between different DE subtypes, such as short tear break-up time DE (sBUTDE) and aqueous tear-deficient DE (ADDE), is essential for elucidating underlying pathophysiological mechanisms.

Purpose of the Study:

• To investigate the association between autonomic nerve activity and symptom intensity in patients with different types of dry eye.
• To determine if parasympathetic and sympathetic nerve activity, as well as their fluctuations, correlate with dry eye symptom severity.

Main Methods:

• A prospective, cross-sectional study involving 25 patients with sBUTDE and 24 patients with ADDE.
• Autonomic nerve activity was assessed using heart rate variability (HRV) parameters, including low-frequency (LF) and high-frequency (HF) components, and their variations (cvRR, ccvLF, ccvHF).
• Symptom intensity and stress levels were evaluated using the Japanese version of the Ocular Surface Disease Index (J-OSDI) and a stress questionnaire.

Main Results:

• In sBUTDE, higher J-OSDI scores significantly correlated with increased parasympathetic activity (HF) and its fluctuation (ccvHF), as well as higher subjective stress.
• No significant correlations were found between J-OSDI scores and autonomic parameters or stress in the ADDE group.
• These findings suggest a differential involvement of the ANS in the symptom experience of distinct dry eye subtypes.

Conclusions:

• Dry eye symptoms in sBUTDE are significantly associated with the magnitude and fluctuation of parasympathetic nerve activity.
• Parasympathetic activity plays a role in the development of symptoms specifically in sBUTDE.
• The autonomic nervous system's involvement in symptom generation appears minimal in ADDE, suggesting different underlying mechanisms for each subtype.