Sympathetic-parasympathetic Ratio of Our Gaze

ABSTRACT BACKGROUND The existence of the retinohypothalamic pathway suggests that light may influence autonomic outflow activity. The objective of this study was to examine the correlation between the estimated iris muscle sympathetic-parasympathetic area (IRIS) ratio and the sympathetic-parasympathetic ratio (low frequency \[LF\]/high frequency \[HF\] ratio). METHODS The study population consisted of 200 females and 200 males (mean age, 32.4 ± 7.1 years). The IRIS ratio was determined from digital photographs of the iris in a computer setting. The LF/HF ratio was determined from records of heart rate variability obtained using a Holter implementation.