A true, naturally occurring violet eye color is extremely rare in humans. Violet is not a pigment produced directly for the iris, but rather an optical effect resulting from specific biological conditions or a unique combination of light scattering and very low pigmentation. The appearance of violet eyes is generally an illusion created by the interaction of deep blue coloration with light reflecting off the internal structures of the eye. Two primary mechanisms can make human eyes appear this color.
How Human Eye Color is Determined
Human eye color is a complex trait determined by the amount of melanin in the iris and how light interacts with the iris’s structure. Melanin, a dark brown pigment, is the only true pigment present in the human iris. High concentrations of melanin in the stroma, the front layer of the iris, result in brown eyes because the pigment absorbs most of the light entering the eye.
Conversely, eyes that appear blue, green, or gray contain very little melanin in the stroma. These colors are not due to a blue or green pigment, but rather to the Tyndall effect. When light enters the stroma, the shorter, blue wavelengths are scattered back out, while the longer, red wavelengths pass through and are absorbed by the dark, melanin-rich layer at the back of the iris.
The Appearance of the Violet Hue
The appearance of a violet hue is an extension of the light scattering that creates blue eyes, occurring when the melanin levels in the stroma are exceptionally low. Eyes that appear violet are essentially a variation of very deep blue or gray eyes, where the Tyndall scattering is intensified. This deep blue color then mixes with light reflecting off the highly vascularized structures at the back of the eye, which contribute a subtle red or pink undertone. The combination of intense blue scattering from the stroma and the faint red light reflecting from the blood vessels creates the perception of a violet color.
External factors, such as the color of a person’s clothing, makeup, or the ambient light, can significantly enhance this optical effect. For instance, the famous “violet eyes” of actress Elizabeth Taylor were a rare, deep blue or indigo that appeared purple under the intense, controlled lighting of a Hollywood set and when she wore specific colors. Her eyes contained a specific, rare amount of melanin that placed their color at the extreme dark end of the blue-gray spectrum.
Violet Eyes and Ocular Albinism
The closest condition to a true reddish or violet coloration is associated with severe forms of albinism, a genetic disorder characterized by a complete or near-complete lack of melanin pigment. In cases of oculocutaneous albinism, the iris lacks its protective pigment entirely, making it translucent. This absence of pigment means the iris cannot absorb or scatter light in the typical way.
Instead of seeing a color determined by melanin or the Tyndall effect, the observed color comes directly from the reflection of the rich red hemoglobin in the blood vessels of the retina at the back of the eye. Under certain lighting conditions, this red reflection can combine with the minimal blue light scattering that still occurs, resulting in a reddish-pink or violet appearance. This lack of pigment also causes significant vision issues, including high light sensitivity and poor visual acuity, because the iris cannot effectively filter light entering the eye.