Surely you have heard the popular saying "the eyes are the mirror of the soul" to refer to how much we can express with them. A pair of identical mirrors that allow us to see the world and appreciate its wonders. But what happens when our eyes are not identical, and what is it called to have one eye of each color?
The first thing you should know is that the colored part of your eyes is called the iris and its shade depends on your genetic heritage. Eyes with brown shades are the most common in the world, followed by blue shades and finally green. Different colored eyes are a genetic anomaly known as heterochromia.
Although it is a rare condition, more and more people have it, including a couple of stars. Did you know that popular movie actor Henry Cavill has a type of heterochromia in his right eye? Modeling legend, producer and actress Demi Moore also has the condition. Interested to know more? Here's everything you need to know about heterochromia, its types, causes and possible consequences.
What is heterochromia of the iris?
Heterochromia iridis is the medical term used to describe the condition that causes a person to have different colored eyes. This condition is usually diagnosed after the age of two. This is because before this age it is impossible to determine precisely what color the eyes will be when the baby grows up.
The hue of our eyes is directly related to the concentration of melanin in the front layers of the iris. Melanin is a chemical biopolymer responsible for pigmentation in our body. As we grow, the cells that produce melanin mature and as their concentration increases, our skin, hair and, of course, eyes darken.
Heterochromia of the iris is not a condition exclusive to humans, several animals also have it. Some dog breeds present this peculiarity more frequently, Siberian husky, Australian shepherds and Dalmatians are some examples. Although it is more common in dogs and cats, other animals such as cows, goats and horses can also present heterochromia of the iris.
Generally, heterochromia is considered to be an anatomical trait that has no negative impact on a person's life. However, it is necessary to have it diagnosed by an eye care professional to rule out the existence of an underlying condition.
Types of heterochromia
Now that you know what it is called to have one eye of each color, it is important to recognize the different types of heterochromia that exist. Although it affects only 1% of the world's population, heterochromia has a wide range of variants. These are classified according to the coloration of the eyes and the time of onset.
Here is a brief explanation of everything you need to know about each type of heterochromia:
Complete heterochromia
Describes the variant in which the eyes have a totally different color from each other. That is, each iris has a different level of pigmentation due to the concentration or scarcity of melanocytes on its surface. An example of complete heterochromia would be one eye with a green iris and the other with a dark brown iris.
Complete heterochromia is perhaps the most striking type because of the clear difference between the two eyes. However, it is a rare variant in human eyes. It is most common in cats, which usually have white fur and one green and one blue iris. It is also common in dogs of the Siberian Husky, Australian Shepherd and Border Collie breeds.
Central heterochromia
This variation is characterized by the color in the central area of the iris being different from that of the periphery of the iris. This phenomenon forms a ring of color around the pupil that constrains the rest of the iris. Usually, the other eye shares the same color as the outer part of the iris with heterochromia.
In these cases, the color difference is less obvious than in cases of complete heterochromia. Although very rare, it may also be the case that both eyes have central heterochromia.
Partial heterochromia
This is the most common type of heterochromia and occurs when one of the irises has double coloration. Often, it is a small "spot" of a different color than the rest of the eye. Henry Cavill, the actor who played Superman and Geralt in The Witcher series, has partial heterochromia.
Acquired heterochromia
Acquired heterochromia is a change in eye color when it occurs after the first years of life. It may appear as a consequence of trauma or some underlying pathology. In any case, it is important to attend an ophthalmologic consultation to rule out possible complications.
Congenital heterochromia
Congenital heterochromia is the difference in color of the eyes of some babies at birth. It is also considered congenital when this difference develops during the first months of the patient's life. Although heterochromia does not usually affect visual health, it is important to have it evaluated by a professional to ensure your well-being.
What are the causes of heterochromia?
Congenital heterochromia is usually a genetic inheritance that is transmitted from generation to generation in a recessive manner. This means that its main cause is due to natural genetic factors.
Heterochromia can also be caused by different factors, both external and internal. Here are some of the causes of acquired heterochromia:
Trauma
The color of the iris can change as a result of a blow to the eye. It is popularly believed that the legendary musician David Bowie had heterochromia as a consequence of a blow he received in his youth. However, his actual diagnosis was anisocoria, an asymmetry caused by permanent dilation of the left pupil.
Glaucoma
Glaucoma itself does not cause a change in the coloration of the iris, but some of the medications used to treat it do.
Other vision pathologies
There are some diseases that could generate a change in the pigmentation of the iris in one or even both eyes. It is important that, if this occurs, you consult an eye care professional immediately. Acquired heterochromia may be a symptom of an underlying disease.
How does a person with different colored eyes see?
Heterochromia only has an aesthetic impact, since it is not a condition that affects health in any way. Those who have this condition congenitally see exactly the same as a person with both eyes of the same color.
Beyond the exoticism that the color difference may generate, patients with heterochromia do not suffer any loss in the quality of their vision.
On the other hand, those with acquired heterochromia may have some variation in their vision. However, such variation would be a consequence of the underlying pathology and not of the heterochromia itself.
Diagnosis and treatment of heterochromia
Heterochromia in the infant's eyes is commonly noticed by the parents within a couple of months of birth. A pediatrician can diagnose the condition and refer to a pediatric ophthalmologist to determine the exact causes. The specialist will assess for damage and prescribe treatment if necessary.
If the color difference is due to genetic factors, then it should not pose a problem for the person's vision. In general, heterochromia does not require any special treatment.
In the case of acquired heterochromia, the physician should evaluate the symptoms and rule out possible underlying pathologies. If necessary, he or she will prescribe treatment and guide the patient to speed recovery.
Conclusion
Heterochromia of the iris is a rare condition that causes the iris of one eye to have a different coloration than the other. It is a characteristic trait that is not exclusive to people, as different animals can also have it. Although it usually does not represent any health hazard, it is important that it be diagnosed by a professional.
Currently, it has become quite a popular trait among people around the world. This may be because several global stars such as Kate Bosworth, Xavi Hernandez, Henry Cavill and Demi Moore have heterochromia. Because of this and the exotic look of those with the condition, many people pretend to have it by wearing contact lenses.
Whether you have heterochromia or you pretend to have it by wearing contact lenses, keep in mind that you must take care of your vision. We recommend that you visit your ophthalmologist at least once a year for a routine checkup. Also, remember to renew the formula of your prescription glasses if necessary and protect yourself from UV rays using the best sunglasses.
