Iris Color and Day-Night Changes in the Sympathovagal Ratio

Study Overview
=================
Brief Summary
-----------------
Iris melanocytes are innervated by parasympathetic and sympathetic nerve endings. Light affects autonomic nervous system activity via the retino-hypothalamic pathway. The hypothesis that the day-to-night variations in the sympatovagal ratio (LF/HF) may differ among individuals with different brown iris patterns was tested.

Detailed Description
-----------------
A total of 621 healthy adults, aged between 16 and 50, with brown eyes and not diagnosed with a disease that might affect the autonomous nerve system were included in the study. A digital camera was used to acquire iris photos. Subjects were grouped into iris color groups (2-0 bg, 1-0 bg, 1-1 db, 1-1 lb, 2-0 b, and 1-0 b). Iris photos were analyzed with Picture Color Analyzer RBG software. The Central/Peripheral (R/RGB) ratio was used for objective distinction between the groups. Using 24-h Holter ECG monitoring, the change in the sympathovagal ratio from day (between 07:00 and 23:00 hrs) to night (between 23:00 and 07:00 hrs) was determined with the formula [(Day - Night) LF/HF)/Day LF/HF].

Official Title
-----------------
Iris Color and Day-Night Changes in the Sympathovagal Ratio

Conditions
-----------------
Iris Diseases

Intervention / Treatment
-----------------
* Other: Iris Color Measurement , LF/HF Measurement


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: A total of 650 healthy individuals between the ages of 16 and 50 . Exclusion Criteria: Diseases that could affect the autonomic nervous system; Obesity Obstructive sleep apnea syndrome Hypertension Diabetes mellitus Atrial fibrillation Coronary disease Heart failure Goiter, etc.

Ages Eligible for Study
-----------------
Minimum Age: 16 Years
Maximum Age: 50 Years

Sexes Eligible for Study
-----------------
All

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| 2-0 darkbown-green (2-0 bg)<br>Those with distinctively dark brown in the central area, slightly green in the peripheral area, | Other: Iris Color Measurement , LF/HF Measurement<br>* Iris Color Measurement (Photos were taken of the iris with a digital camera ) LF/ HF Measurement (Using the three-channel standard ambulatory Holter recording system)<br>|
| 1-0 lightbrown-green (1-0 bg).<br>Those with slightly dark brown in the central area and green in the peripheral area, | Other: Iris Color Measurement , LF/HF Measurement<br>* Iris Color Measurement (Photos were taken of the iris with a digital camera ) LF/ HF Measurement (Using the three-channel standard ambulatory Holter recording system)<br>|
| dark brown (1-1 db)<br>Eyes with the same color structure in the central iris and the peripheral iris. | Other: Iris Color Measurement , LF/HF Measurement<br>* Iris Color Measurement (Photos were taken of the iris with a digital camera ) LF/ HF Measurement (Using the three-channel standard ambulatory Holter recording system)<br>|
| light brown (1-1 lb)<br>Eyes with the same color structure in the central iris and the peripheral iris. | Other: Iris Color Measurement , LF/HF Measurement<br>* Iris Color Measurement (Photos were taken of the iris with a digital camera ) LF/ HF Measurement (Using the three-channel standard ambulatory Holter recording system)<br>|
| dark brown (2-0 b)<br>Those with distinctively dark brown in the central iris area compared to the periphery . | Other: Iris Color Measurement , LF/HF Measurement<br>* Iris Color Measurement (Photos were taken of the iris with a digital camera ) LF/ HF Measurement (Using the three-channel standard ambulatory Holter recording system)<br>|
| slightly dark brown (1-0 b)<br>Those with slightly dark brown (1-0 b) in the central iris area compared to the periphery . | Other: Iris Color Measurement , LF/HF Measurement<br>* Iris Color Measurement (Photos were taken of the iris with a digital camera ) LF/ HF Measurement (Using the three-channel standard ambulatory Holter recording system)<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| LF/HF ratio | low frequency (LF, 0.04-0.15 Hz) and high frequency (HF, 0.16-0.4 Hz) measurements were taken from day and night changes in the heart rate by using the frequency-domain analysis method. | one week | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
LF/HF ratio, iris color, melanin