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Have you ever seen someone with fascinating eyes? Perhaps they were each two different colors or, maybe, the eyes seemed to have different colors within each iris. There is a name for this.
Heterochromia is the eye condition characterized by color differences in your iris, the colored part of your eye.(2) This may occur between the two eyes or within one eye. Central heterochromia, in particular, is characterized by differences in pigmentation in the same eyes.
Central heterochromia causes a color abnormality that looks like it stems from the pupil at the center of the eyes, like cat eyes. Due to an uneven distribution of melanin, the outer ring will almost always be blue or green. And it is common for the inner ring to be gold or hazel. So the person may appear to have hazel eyes.
Most of the time, central heterochromia happens sporadically, without any real causes for concern.(3) However, rarely, heterochromia is linked to a congenital syndrome, such as Waardenburg syndrome, Parry-Romberg syndrome, Horner's syndrome, or Sturge-Weber syndrome.(2)
Treatment is not typically necessary to treat this eye condition unless there are underlying causes behind the difference in each eye’s iris color or unless it is congenital heterochromia. Otherwise, heterochromia does not typically affect someone’s eye health or vision.
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There are different types of heterochromia. One affects the same eye and the other affects both eyes:
Segmental heterochromia is also known as heterochromia iridum, sectoral heterochromia, or partial heterochromia.
Again, it occurs when different areas of the same iris vary in pigment.(3) For example, someone might have blue eyes with bits of brown or brown eyes with a patch of green.
Someone with this type of heterochromia might appear to have speckled eyes. The speckle can be very interesting to see, though it is not always obvious. You may not notice segmental heterochromia from far away unless you look up close.
Complete heterochromia, also known as heterochromia iridis, refers to when the iris in one eye is a different color than the iris in the other eye. So someone who has totally different colored eyes might have complete heterochromia.(3)
For example, someone might have one blue eye and one brown eye. Or they might have one green eye and one blue eye. The color variation can be with any two colors.
Eye color is determined by gene variations. Most genes that are linked to eye color produce, transport, or store a pigment called melanin.(4)
A typical iris consists of five layers.(1)
The amount of melanin in the front layers of the iris causes eye color.(5) So someone with a lot of melanin might have brown eyes, while someone else with less melanin may have a lighter eye color, such as blue or green eyes.
Of course, some people wear colored contact lenses to change the look of the color of their eyes, too.
Looking in direct sunlight and wearing certain colors (especially like bright colors that accentuate your eye color) can also tend to change the appearance of the color of your eyes. For example, while wearing a blue T-shirt does not make green eyes blue, the reflection can make them appear more bluish than greenish.
Heterochromia is a rare eye condition, but it’s also rarely an eye health concern. Fewer than 200,000 Americans have the condition.(6)
If you have central heterochromia, you are not alone. In fact, some famous people have heterochromia. Mila Kunis and Kate Bosworth are both believed to have it.
Central heterochromia is typically a benign condition that occurs because of the uneven distribution of melanin. It’s not usually caused by a medical condition or eye disease like glaucoma. And it does not usually affect vision.(3)
Central heterochromia can happen due to an eye injury or eye inflammation. You should see an ophthalmologist for an eye exam if you notice that the iris in one or both of your eyes has changed color.
To be diagnosed for central heterochromia, you must see a doctor who specializes in ophthalmology. This eye doctor will do a routine eye exam to look for uneven or totally different pigment dispersion in one or both eyes.
If you are diagnosed with central heterochromia, it’s typically not a cause for concern. But your eye doctor may ask you questions to find out if there is an underlying health condition that has caused your difference in eye color.
If you do have an underlying eye condition or have had an eye injury that has caused heterochromia, your eye doctor may recommend a specific course of action. You may need to see another type of doctor to treat that specific condition, which may help this particular symptom.
There are no treatments for central heterochromia.(3) Central heterochromia does not generally affect people’s eyesight, so treatment isn’t really necessary.
Some people may choose to wear colored contact lenses in both eyes to change the color of their eyes. Or they may wear one colored contact lens to match the color of the other eye. Contacts are just for aesthetics and personal choice.
If you do choose to wear colored contacts, talk to your eye doctor about contacts that are right for you. You will need a proper eye exam to get a contact prescription. If you do not need corrective lenses, you can still buy colored contacts that are strictly cosmetic.
Most people who have central heterochromia are perfectly healthy. The eye condition is not typically known to affect their eye health, general health, or vision. Therefore, people who live with central heterochromia have an excellent prognosis.
That said, it’s important to talk to your eye doctor about changes in your eye color. You always want to be sure to rule out any underlying causes, even though they tend to be rare.
Edwards, Melissa, et al. “Iris Pigmentation as a Quantitative Trait: Variation in Populations of European, East Asian and South Asian Ancestry and Association with Candidate Gene Polymorphisms.” Wiley Online Library, John Wiley & Sons, Ltd, 22 Dec. 2015, onlinelibrary.wiley.com/doi/10.1111/pcmr.12435.
“Heterochromia Iridis.” Genetic and Rare Diseases Information Center, U.S. Department of Health and Human Services, rarediseases.info.nih.gov/diseases/8590/heterochromia-iridis.
“Heterochromia.” American Academy of Ophthalmology, 19 Apr. 2021, www.aao.org/eye-health/diseases/what-is-heterochromia.
“Is Eye Color Determined by Genetics?: MedlinePlus Genetics.” MedlinePlus, U.S. National Library of Medicine, 18 Sept. 2020, medlineplus.gov/genetics/understanding/traits/eyecolor/#.
Rennie, I G. “Don't It Make My Blue Eyes Brown: Heterochromia and Other Abnormalities of the Iris.” Eye (London, England), Nature Publishing Group, Jan. 2012, www.ncbi.nlm.nih.gov/pmc/articles/PMC3259577/.
Ur Rehman, Habib. “Heterochromia.” CMAJ : Canadian Medical Association Journal = Journal De L'Association Medicale Canadienne, Canadian Medical Association, 26 Aug. 2008, www.ncbi.nlm.nih.gov/pmc/articles/PMC2518194/.