Naturally purple eyes do not exist in humans due to true purple pigment. However, certain rare genetic conditions or specific lighting scenarios can make eyes appear violet.
The Science Behind Eye Color
Human eye color is primarily determined by the amount and type of melanin present in the iris, the colored part of the eye. Specialized cells within the iris called melanocytes produce melanin, which exists in two main forms: eumelanin, responsible for brown and black hues, and pheomelanin, which contributes to red and yellow tones. The concentration and distribution of these melanin types dictate the perceived eye color. For instance, brown eyes contain high levels of melanin, which absorbs most light entering the eye.
In contrast, blue eyes have a very low melanin content, allowing light to scatter within the iris’s stroma, a phenomenon known as Rayleigh scattering. This process preferentially scatters shorter, blue wavelengths of light, making the eyes appear blue, similar to how the sky appears blue. Green and hazel eyes result from intermediate levels of melanin combined with this light scattering effect, often involving a mix of both eumelanin and pheomelanin. The human iris does not contain actual blue or green pigments; these colors are structural, arising from how light interacts with the iris’s composition.
When Eyes Appear Violet
The appearance of violet or purple eyes is most significantly associated with severe forms of albinism, a genetic condition characterized by reduced or absent melanin production throughout the body, including the eyes. In individuals with ocular albinism, the extreme lack of melanin in the iris allows light to pass through the eye tissue more readily. This transparency reveals the red light reflecting off the blood vessels at the back of the eye, a phenomenon similar to the “red-eye” effect seen in flash photography.
When this visible red reflection from the underlying blood vessels combines with the blue light scattered by the collagen fibers in the iris, a unique violet or purplish hue can be created, particularly under certain lighting conditions. This violet appearance is exceptionally rare, occurring in less than 1% of the global population, as albinism itself affects approximately 1 in 18,000 to 20,000 people in the U.S., and not all individuals with albinism exhibit violet eyes. People with albinism often experience additional vision challenges, such as sensitivity to light and involuntary eye movements, due to the lack of protective melanin.
Understanding What Looks Purple
Beyond the rare instances related to albinism, eyes can sometimes appear purple due to external factors and visual perception. Certain shades of blue or grey eyes, for example, may take on a violet tint under specific circumstances. This perceived change in color is often influenced by the type and intensity of ambient lighting, with soft indoor light or particular angles enhancing a purplish cast. The colors of clothing worn near the face or the use of photographic filters and editing can also contribute to this optical illusion, making eyes seem more violet than their inherent color.
The famous actress Elizabeth Taylor’s eyes, often described as violet, were in fact a deep blue-grey shade that appeared purplish due to a combination of her unique eye structure, strategic makeup, and specific lighting conditions. Furthermore, fictional works often portray characters with striking purple eyes, contributing to the popular, yet scientifically unfounded, notion of naturally pigmented violet eyes.