Experimental study of reliable iris parameters and their relationships with temperament, character, and heart rate variability

Abstract

Introduction

While many studies have indicated that iris parameters are not a valid tool for disease diagnosis, it is still uncertain whether these parameters are more closely related to inherited characteristics or overall functional parameters. The aim of this study was to examine the relationship between the iris, overall functional parameters, and inherited characteristics of individuals.

Methods

A total of 117 healthy volunteers (42 men, 75 women) participated in our study. After photographing each subject’s iris, we graded six iris parameters: iris density, pigment dots, nerve ring, toxic radii, autonomic nerve wreath ratio, and pupil area ratio. We randomly selected 30 samples and conducted intra- and inter-rater reliability tests. To measure inherited characteristics, each subject completed a temperament and character inventory (TCI). To measure functional markers, we calculated frequency domain (TP, VLF, LF, and HF) parameters of heart rate variability (HRV) using 5-min ECG recordings. Finally, we examined the relationships between iris characteristics, HRV parameters and TCI measurements.

Results

Intra- and inter-rater reliabilities of the six iris parameters were high, with intra-class correlation coefficients ranging from 0.868 to 1.000. Among the iris parameters, nerve ring, iris density, and pupil area ratio parameters were related to novelty seeking, persistence, harm avoidance, and self-directedness subscales of the TCI. The relationships between iris characteristics and HRV parameters were weaker. These relationships were more prominent in men than in women.

Conclusions

We concluded that iris parameters are more likely to be determined by inherited characteristics than functional changes and were more prominent in men than women.

European Journal of Integrative Medicine

Volume 6, Issue 5, October 2014, Pages 524-531