To the researchers, the eye doesn’t contain any pigments that give it its color: it’s a light dispersion effect.
Author: ANDRÉS ALBURQUERQUE / Photo: IMDB
They are almost certainly the most praised eyes of Hollywood actors. Only rivaled by Elizabeth Taylor’s Violet. “King of Cool,” they nicknamed the man with the bluest, deepest eyes in the history of movies: Paul Newman. However, science now tells us that blue eyes do not exist.
The nearly transparent blue look that dazzles the world in The Long Summer or Cat on a Hot Roof is a farce.
But how is that possible if we see them that color? Despite how they appear to the naked eye, they are not truly blue because the human eye does not provide blue pigments of this hue.
The answer to this puzzle is the same as scientific explanation for the blueness of the sky or the greenness of the sea.
Color is nothing more than the way our eyes interpret light from different objects around us. Therefore, the color is only light. So what does this interpretation and the different tone we see depend on? Well, it’s nothing more than the amount of light these objects absorb or reflect.
Light consists of a set of wavelengths, each identified by a color: the longest wavelength is red, orange, or yellow; . While the shorter ones are identified by blue and purple hues.
So when light reaches an object, it absorbs or reflects some of it, depending on the material of the object, thus determining its color. Those reflected rays reach your eyes and your brain converts their wavelengths into color, which you associate with the hue of the object, while those that are absorbed don’t contribute to the assignment of hue.
So, what happens with blue eyes? They don’t have any blue pigments to color them, but the blue hue is entirely due to the behavior of the iris: it absorbs long wavelengths of light, thereby reflecting the hues associated with blue. This is not the case with brown, where melanin (a substance also associated with darker colors in hair or skin) is located in the iris, directly dyeing it brown.
This area of the iris is responsible for providing color to the human eye. It consists of two main layers: pigment epithelium and stroma. The first is the epithelium, which nearly all humans contain some amount of melanin, the brown pigment. The protagonist in this aspect of tonality is therefore the second layer, the matrix, which consists of a series of overlapping fibers and a large number of specialized cells.
If the matrix lacks pigment, the fibers are dispersed throughout the area, which means they absorb long wavelengths and reflect short wavelengths, the blue tint, causing the eye to see other colors. However, when the stroma contains melanin, it combines with the melanin on the back, covering the iris and coloring it brown.
Green eyes, on the other hand, are a strange combination of the two conditions. Therefore, as in brown people, for this hue to occur, there must be very little melanin in the matrix, accompanied by a very light brown pigment called lipochrome. Thus, the absence of melanin will result in a bluish tint due to reflection of light, but the presence of lipochromes will combine to produce a green tint.
This explains why some babies usually have blue eyes until they are one year old, but later change to brown or brown eyes. This is because there is not much melanin at birth, and it is during the first year of life that this pigment accumulates, turning the baby’s irises dark.