Depending on genetics, people’s eye color can vary. In fact, the shades of blue, green, or gray eyes respond to alterations inherited from your parents and can be maintained for generations and generations. The most common phenotype in human eyes is brown, brown, or brown.
However, can you imagine that your eyes had a different color each? Well, we tell you that this phenomenon does exist. We refer to a condition known as Heterochromia. It is an abnormality in the eyes, especially in cats and dogs such as the Siberian Husky, Dalmatian, Border Collie, and Australian Shepherd. However, this phenomenon has become frequent, although to a lesser extent, in human beings.
The different shades of iris in the eye globules are due to a high concentration or lack of melanin. In case you don’t know, melanin is the body compound responsible for producing pigment or color.
How Is the Color of the Eyes Produced?
Between the ages of 6 and 10 months, some children may have an eye color similar to gray or light blue. After this period, the final tone is formed, which depends exclusively on the number of cells that make up melanin, which is called melanocytes.
If these melanocytes are concentrated on the back surface of the iris, the eye will appear blue. On the other hand, if they are distributed throughout the iris’ thickness, the tone will be brown or brown. That said, it is understood that the distribution of these cells will determine the eyes’ color. In any case, this phenomenon is affected too much by the genetics of each person.
Types of Heterochromia
As you can imagine, there is no single type of Heterochromia. Like it or not, this condition can manifest itself in different ways that we will review below:
Total or Complete: It is when the color of one eye is different from the other.
Partial: It occurs when one of the irises has some discoloration or « stain » compared to the other eye. Usually, this version comes from inherited diseases, such as Waardenburg syndrome and Hirschsprung’s disease.
Central Heterochromia: This is a curious phenomenon in which you can see a ring of one color, and the iris has another hue in one or both eyes. It is essential to know that when you have this type of Heterochromia, it must be clarified that the actual color is actually the outer ring. At the same time, the central one shows the color affected by the condition.
Dominant Eye Colors in Humans
At least 50% of the world’s population has brown eyes (in their different shades). That would explain why people with light tones are so striking.
According to the Institute of Evolutionary Biology of Barcelona, the blue color is the world’s rarest and could be older than 10,000 years.
Only 2% of the world’s population has this hue. This is due to a low proportion of melanin and a lot of lipochrome (a yellowish pigment), which generates green. Curiously, this color is more frequent in women than in men and tends to occur in a higher proportion in continental Europe. In Hungary, around 20% of the population has green in the eyes. On the other hand, in Iceland, it is present in at least 80% of the inhabitants.
This color does not really exist, as it is due to a strange mixture of copper tones and blue reflections that create this almost lilac or violet coloration. It can only be evidenced when this individual is exposed to light. One of the known people with this shade was the famous actress Elizabeth Taylor.
It should be noted that although in most people, this condition occurs from birth, there is also acquired Heterochromia. This means that the anomaly appears at an advanced age, produced by some trauma to the eyes and by using certain drugs necessary for a disease such as glaucoma.
Similarly, it can be caused by some bleeding in the eye, including uveitis disease, which is the inflammation of the middle layer of the eyeball. In the worst case, tumors affecting the vision could also cause pigmentation changes. Therefore, to be sure of the color change cause, we recommend that you go to a specialist who will thoroughly examine your eye globules.
That way, you could avoid some diseases that can put your vision at risk in the future, thereby reducing your quality of life.