Autonomic dysfunction in obstructive sleep apnea syndrome: a pupillometric measurement study.

Purpose: It has been suggested that obstructive sleep apnea syndrome (OSAS) is associated with an imbalance in autonomic nervous system (ANS) tone. Pupil size is regarded as a reliable indicator of ANS function. Pupillometry, a straightforward and non-invasive technique, is used to measure both the size and dynamics of the pupil. This study aimed to investigate, through pupillometry, the hypothesis that individuals with OSAS exhibit dysregulation of the autonomic nervous system.

Methods: In this study, OSAS patients and a control group of healthy individuals were included. OSAS patients were divided into mild, moderate, and severe groups according to their apnea-hypopnea index (AHI) scores. In the study, mild sleep apnea is defined as an AHI between 5 and 14, moderate sleep apnea as an AHI between 15 and 29, and severe sleep apnea as an AHI of 30 or higher. Static and dynamic pupillometric measurements were performed in both groups under scotopic, mesopic, and photopic conditions using a digital infrared pupillometer to evaluate autonomic dysfunction.

Results: The mean age of the study participants was 52.1 ± 10.4 years. A significant difference was observed between the groups in terms of mean AHI value (p < 0.001). There was no significant difference between the groups for static scotopic, mesopic, photopic pupil measurements (p > 0.05). However, significant differences were found for dynamic pupillary measurements (D1) (p = 0.023) and post-hoc analysis showed a significant difference between the control group and the severe OSAS group (p < 0.001). Correlation analysis revealed a significant correlation between age and AHI (r = 0.269, p = 0.003) and Moreover, a significant negative correlation was observed between AHI and D1 (r = -0.323, p < 0.001).

Conclusion: In this study on pupillary measurements in OSAS patients, no significant difference was found in static pupillary responses in OSAS patients, whereas dynamic pupillary responses were found to be significantly impaired in severe OSAS. The significant impairment in severe OSAS suggests autonomic dysfunction due to hypoxia-induced neuronal damage. In conclusion, pupillometry may be a simple, noninvasive approach to detect ANS dysfunction in OSAS patients.