Can dynamic and static pupillary responses be used as an indicator of autonomic dysfunction in patients with obstructive sleep apnea syndrome?

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.

Evaluation of Static Pupillary Parameters in Pediatric Patients with Vitamin B12 Deficiency

BACKGROUND

Automatic pupillometry device enables important information about pupillary function. Neurological manifestations such as autonomic dysfunction and ophthalmological disorders are observed in vitamin B12 deficiency (VB12D).

AIM

To assess the static pupillary functions using a pupillometry device in pediatric patients with VB12D.

METHODS

The study included 40 children with VB12D and 40 healthy children in the control group. The measurements were made with an automated pupillometry under static conditions. The static measurements were performed at scotopic, mesopic, and photopic light intensities. The differences between the patient and control groups were analyzed with static measurements.

RESULTS

Pupillary diameters of the patient and control groups under scotopic, mesopic, and photopic conditions were observed and there was a statistically significant difference under the mesopic and photopic conditions. Under mesopic conditions: The mean pupil diameter was found to be 5.92 ± 0.69 mm in the VB12D group and 5.18 ± 0.91 mm in the control group (P = 0.003). Under photopic conditions, the mean pupil diameter was found to be 5.13 ± 0.77 mm in the VB12D group and 4.53 ± 0.96 mm in the control group (P = 0.001). Under scotopic conditions, the mean pupil diameter was 6.46 ± 0.68 mm in the VB12D group and 6.37 ± 0.93 mm in the control group. There was no statistically significant difference between the patient and control groups in the measurements under scotopic conditions (P = 0.63).

CONCLUSION

Pediatric patients with VB12D have significantly larger pupil diameters in photopic and mesopic conditions than healthy children. The results suggest that there is an autonomic system dysfunction in children with VB12D, especially when the parasympathetic system is negatively affected. Pupillary contraction is reduced in children with VB12D. Decreased pupillary myosis function is observed. Pupillary size is larger in vitamin B12-deficient children under photopic and mesopic conditions.

Do static and dynamic pupillary parameters differ according to childhood, adulthood, and old age? A quantitative study in healthy volunteers

Purpose

We aimed to evaluate the normative pupillometry values and mean pupil dilatation speed in healthy individuals in different age groups in our study.

Methods

The study group included 180 eyes of 90 healthy volunteers in different age groups. Group 1 consisted of 30 participants between the ages of 6 and 18, group 2 consisted of 30 participants aged 19-40, and group 3 consisted of 30 participants aged 41-75. Scotopic, mesopic, photopic, and dynamic measurements were taken with automatic pupillometry of Sirius Topographer (CSO, Firenze, Italy). The mean pupil dilation speed at the 18^th second was calculated according to dynamic measurements.

Results

Group 1 had a significantly larger pupil diameter than groups 2 and 3 in all static and dynamic parameters, and the mean pupil dilation speed was the highest among the groups (P < 0.001 for all static and dynamic parameters). In addition, group 2 had a significantly larger pupil diameter than group 3 (P < 0.001 for all static and dynamic parameters) and the mean pupil dilation speed was faster than group 3 (P = 0.027).

Conclusion

We have presented the static and dynamic parameters and the mean speed of pupil dilatation at the 18^th second with automatic pupillometry in healthy individuals in childhood, adulthood, and old age. More studies with higher participants and younger age children are needed.