Vairons Eyes: How to explain it?
To have small eyes means to present two irises of different colors. Eye color is determined by the amount and distribution of melanin in the iris, which can be blue, green, brown … But by what miracle a person can have two eyes of different colors? Is this problematic?
Why do we have wall eyes?
Wall eyes are the result of a genetic defect linked to congenital heterochromia . This term refers to the difference in hue at the level of the iris, derived from an excess or a lack of melanin. If this feature remains rare in humans, it is, on the other hand, more common in animals. It is even quite common among certain breeds of dogs, in particular the Australian Shepherd or the Siberian Husky.
We can distinguish according to two parameters according to which heterochromia can emerge: localization and the manifestation. Indeed, it may be that the heterochromia is not necessarily total. The whole iris, like a small part, can be reached. A complete heterochromia (or iris or bilateral) , is materialized by two irises of different colors, and therefore two eyes of different colors.
In contrast, partial heterochromia , also called Iridis or unilateral, is characterized by different colors on the same iris. This peculiarity is much more frequent than complete heterochromia . Only certain areas of the eye have different colors. This partial heterochromia can be central or sectorial, depending on whether the color forms a ring or a non-circular spot of another color.
In addition, congenital heterochromia manifests itself as soon as the eye color is definitive, ie around 6 months. If the difference occurs later, we will speak of acquired heterochromia. The latter is linked to the vagaries of life (shocks, injuries, illnesses, etc.)
Wall eyes: Causes and effects
Most often, congenital heterochromia is the result of what one might call 'genetic curiosity'. This does not impact visual acuity, either negatively or positively. However, it can be explained by a congenital disease (neurofibromatosis, Waardenburg syndrome and other pigmentation abnormalities.)
When heterochromia is acquired, it can only be due to ocular trauma or pathologies (cataracts, glaucoma, uveitis, melanomas …) Certain foreign bodies can also cause depigmentation of the eye.
There is no treatment to correct this anomaly. Gender does not affect the likelihood of having dark eyes . The probability figures are not known for congenital heterochromia. The only thing we are sure of is that this anomaly remains very rare in humans.
It is nonetheless fascinating. There is no doubt that future studies will tell us more!