Relationship between Iris Color and Skin Color

Kim, Ji Woong; Ahn, Hyo Hyun; Kye, Young Chul

Abstract

BACKGROUND
In a study, iris color was positively associated with skin melanin content. So it could be assumed that iris color has a close relationship with skin color. But until recently, classification system of iris color has been subjective and not suitable especially for Asian population for their relative homogeneity of iris color.
OBJECTIVE
The purpose of this study was to devise an objective and quantitative method to measure iris and skin color quantitatively and to assess the relationship and its significance.
METHODS
We devised photographic system composed of digital camera and tungsten lamp with color temperature conversion filter to acquire adequate iris images for colorimetric investigations. The reference CIELAB coordinates of color chart recorded with reflectance spectrophotometer were compared statistically with computed CIELAB coordinates from digital images in order to find equations for calibrating CIELAB values. To find the dermatological significance, we took pictures of 47 Korean patients with various conditions. They were evaluated with regard to iris color, color of sun-exposed and sun-protected skin.
RESULTS
The images obtained with this system were enough to be used for the assessment of iris and skin color. And, it was possible to quantify the iris color, skin color and its difference in colorimetric ways using the methods in this study. Lightness (L*) of sun-exposed skin is decreased to the age. L* of iris has a positive correlation with L* of sun-exposed skin. L* of iris was positively correlated with a* and b* of iris respectively. The relations were very similar with those between L* of iris and each of a* and b* of sun-protected skin.
CONCLUSION
Iris color could be assessed by using their images colorimetrically obtained by our method. As L* of iris color has the similar relations with a* and b* in both iris and sun-protected skin, the iris color would be a clue to look for and define the constitutional skin color.