Central Heterochromia (Meaning and Types)

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Page last updated: 26/09/2022

Central Heterochromia (Meaning and Types)

In this brief guide, we will look at the meaning and types of Central heterochromia.

Central Heterochromia: Meaning

Central heterochromia is a type of pigment related anomaly in the eye which causes differently colored rings around the iris which may be different in each eye, or simply a different color than the color of the iris.

An example of central heterochromia may be someone who has a gold colored ring around the border of their pupil in the center of their iris, while the rest of their iris is another color, which is the person’s true eye color, for instance.

This means that someone with blue eyes and gold rings has central heterochromia, and this could be due to a variety of reasons.

Central heterochromia can also manifest in the person having different colored borders or specks around the pupil in each eye, which may not look striking suddenly, but it can still make the eyes look slightly different.

Central Heterochromia does not necessarily have to consist of rings around the pupils, it can also be spikes of different colors around the pupil, but the person may not have spikes of different colors.

Everyone has a ring around their pupil or spikes of color around their pupil, but people with central heterochromia have slightly different colored rings around their pupil, and often they may have differently colored rings in either eye.

There are 3 famous people who have central heterochromia — Mila Kunis, Christopher Walken and Alexander the Great.

Mila Kunis has the type of central heterochromia that causes her eyes to look like they are of slightly different colors, while Chrostopher Walken’s eyes do not look like there are differently colored rings per se, but one can see that there is a slight difference of color.

Christopher Walken’s eyes are a good example of how central heterochromia might look when someone has no particular rings around their eyes, and it may be that he actually has differently colored spikes instead.

Central heterochromia is seen most frequently in light blue colored eyes, where the iris is predominantly blue but there are greenish specks or spikes all around the pupil.

Some other people with blue eyes may have a central heterochromia with orange spikes or rings around their pupils which may become more pronounced in sunlight.

Central Heterochromia (Meaning and Types)

Central Heterochromia Causes

Central Heterochromia may be genetic, or it might be caused by illness or injury as well.

Before trying to understand what causes central heterochromia or the condition of heterochromia in general, one first needs to understand the relationship between melanin and eye color. 

Melanin is a pigment that gives human skin and hair their color (should not be confused with Melatonin, which is a hormone that helps regulate sleep and some other biological patterns).

So for instance, someone that has fair skin has less melanin than a person with dark skin, but this does not mean that someone with fair skin simply cannot get darker skin, because melanin can cause the skin to get darker when it is exposed to sunlight for longer periods.

It is simply that because fairer people have lesser melanin, their skin can only get so much darker, however, melanin does not work the same way with eye color, and eye color does not change when exposed to the elements in any way.

The presence of Melanin determines eye color and when people have less pigment in their eyes they also have a lighter eye color than someone with more pigment, so for instance, someone with less pigment in their eyes is more likely to have blue eyes, whereas someone with more pigment may have brown or black ones.

When a person has heterochromia, the amount of melanin in their eyes varies. The variation of melanin in the eyes then causes different colors in different parts of the eye, and even the exact cause of this variation can vary, and there has been no deciding factor about why it happens.

Central heterochromia often occurs sporadically at birth and can appear in someone with no family history of heterochromia, which means that genetics alone do not seem to affect the presence of heterochromia, whether that is central or any other type.

Also, in most cases, unless there is illness or injury, of course, Central heterochromia is a benign condition not caused by an eye disease, and it also does not affect vision, which is why it also doesn’t require any type of treatment or diagnosis.

There may be some cause for concern when people develop heterochromia later in life, however. The central heterochromia that develops at a later stage in life is known as acquired heterochromia, and it may occur from an underlying condition such as:

  • eye injury
  • diabetes
  • pigment dispersion syndrome (pigment released into the eye)
  • eye inflammation
  • bleeding in the eye
  • tumors of the iris
  • Horner’s syndrome (neurological disorder that affects the eye)

Horner’s Syndrome: Possible Reason for Acquired Heterochromia

Horner syndrome is a neurological condition that tends to affect the eye among other things and it is one of the biggest causes of acquired central heterochromia, or other types of heterochromia, for that matter.

Horner’s syndrome is a combination of signs and symptoms that are the result of the disruption of a nerve pathway from the brain to the face and eye on one side of the body.

In most causes, Horner syndrome results in a decreased pupil size, a drooping eyelid and decreased sweating on the affected side of your face, but in some cases it may also be associated with the change in eye color, or central heterochromia.

Horner syndrome usually results as a symptom of another medical problem, such as a stroke, tumor or spinal cord injury, but it is not necessary, and in some cases, no underlying cause can be found. 

There’s also no specific treatment for Horner syndrome, but treatment for the underlying cause may restore normal nerve function.

Horner syndrome is also known as Horner-Bernard syndrome or oculosympathetic palsy.

Horner syndrome usually affects only one side of the face. Common signs and symptoms include:

  • Slight elevation of the lower lid, sometimes called upside-down ptosis
  • Sunken appearance to the eye
  • Little or no sweating (anhidrosis) either on the entire side of the face or an isolated patch of skin on the affected side
  • Central Heterochromia
  • A persistently small pupil (miosis)
  • A notable difference in pupil size between the two eyes (anisocoria)
  • Little or delayed opening (dilation) of the affected pupil in dim light
  • Drooping of the upper eyelid (ptosis)

Types of Heterochromia

There are three types of Heterochromia:

  • Complete Heterochromia: Here each eye is a distinctly different color, such as one blue eye and one brown eye. This is found more in animals and is relatively rare in humans. Even among animals, it is most commonly found in Husky breed of dogs and cats.
  • Central Heterochromia: In this type the eyes show multiple colors, such as a blue iris with a brown ring around the pupil
  • Sectoral Heterochromia: In this type, one iris has a splash of color that’s unique from its overall hue.

Sectoral Heterochromia

Sectoral heterochromia is sometimes referred to as partial heterochromia, and in this type of heterochromia, some areas of the same iris may contain two completely different colors and it is not known exactly how rare sectoral heterochromia is in humans.

There are various reasons for Sectoral heterochromia, depending on whether the iris with the splash of color is lighter or darker, and these are listed below:

When the colored iris is darker:

  • Sturge–Weber syndrome: This is a syndrome characterized by a port-wine stain nevus in the distribution of the trigeminal nerve, leptomeningeal angiomas on the same side of the skull  with intracranial calcification and neurologic signs, and angioma of the choroid, often with secondary glaucoma
  • Lisch nodules: These may be due to iris hamartomas seen in the disorder neurofibromatosis.
  • Oculodermal melanocytosis 
  • Pigment dispersion syndrome: This is a condition characterized by loss of pigmentation from the posterior iris surface which is disseminated intraocularly and deposited on various intraocular structures, including the anterior surface of the iris.
  • Ocular melanosis: This is a condition characterized by increased pigmentation of the uveal tract, episclera, and anterior chamber angle.

However, one needs to remember that these conditions are all serious ones and not one of them will be caused by just the change in eye color, and they represent cases where the eye color changes spontaneously.

Other conditions that may cause sectoral heterochromia, when the iris is lighter, that is, include:

  • Incontinentia pigmenti
  • Parry–Romberg syndrome
  • Simple heterochromia: A rare condition in which there is absence of other ocular or systemic problems. The lighter eye is usually considered to be the affected eye because of the presence of iris hypoplasia which may affect an iris completely or only partially.
  • Congenital Horner’s syndrome
  • Hirschsprung’s disease: This is a bowel disorder associated with heterochromia in the form of a sector hypochromia. The affected sectors have been shown to have reduced numbers of melanocytes and decreased stromal pigmentation.
  • Waardenburg syndrome: This is a syndrome in which heterochromia features as bilateral iris hypochromia in some cases. A Japanese review of 11 children with albinism found that the condition was present in their eyes and all of them had sectoral/partial heterochromia.
  • Piebaldism: This is a condition similar to Waardenburg’s syndrome, and it may be defined as a rare disorder of melanocyte development characterized by a white forelock and multiple symmetrical hypopigmented or depigmented macules.

Conclusion 

In this brief guide, we looked at the meaning and types of Central heterochromia.

Central heterochromia is one of the physical conditions that looks completely fascinating and one naturally wants to know more about it, because it is just so different and unique.

While someone with central heterochromia might feel like they look different from everyone else and have some concerns about themselves because of it, the truth is that it makes them very rare.

If you have any more questions or comments about central heterochromia, please feel free to reach out to us at any time.

Frequently Asked Questions (FAQs): Central Heterochromia

How rare is central Heterochromia in the world?

Central Heterochromia is fairly rare, and only about less than 1 percent of the world’s population has Central heterochromia.

Even though Central Heterochromia is so rare, there are 3 famous people who have this condition, namely, Mila Kunis, Christipher Walken and Alexander the Great.

How do I know if I have central Heterochromia?

If you have central heterochromia, you will know because your two eyes will be different colors, And you will see the two different colors in the same iris. 

What is the most common type of Heterochromia?

The most common type of Heterochromia is Central heterochromia and likely due to this it is not nearly as visually striking as the other types.

Central heterochromia happens when the irises match each other but have a ring of a different color around the pupils.

Is Heterochromia genetic?

Heterochromia can be genetic, but it can also be caused by illness or injury that leads to something going wrong with the pigment-producing cells in the eyes.

Citations

https://www.essilorusa.com/newsroom/what-causes-different-colored-eyes

https://www.healthline.com/health/central-heterochromia#:~:text=What%20is%20central%20heterochromia%3F,of%20their%20iris%20another%20color.

https://www.medicalnewstoday.com/articles/319389

https://en.wikipedia.org/wiki/Heterochromia_iridum