What Is Heterochromia?
Heterochromia is a condition characterized by two differently coloured irises or variations in colour within the same eye. It can occur in several forms: complete heterochromia (heterochromia iridum), where each eye is a different colour; sectoral heterochromia (heterochromia iridis), where a portion of one eye is a different colour; and central heterochromia, where the inner ring of the iris is a different hue from the outer ring. While it occurs in humans, animals like cats and dogs often display this trait as well.
How Do You Get Heterochromia?
Heterochromia can be attributed to genetic factors, such as variations in the OCA2 and HERC2 genes, which are involved in melanin production. There are two types of melanin in mammals eumelanin (brownish black pigmentation) and pheomelanin (reddish/yellow pigmentation). The variation of melanin production amount leads to different iris pigmentation colours.
Heterochromia can also be acquired due to injury, disease, or certain medications. Some eyelash growth serums like Latisse and some topical glaucoma medications such as prostaglandin analogues may change the iris colour. Many people with heterochromia do not have any underlying health issues, however, it is important to see an eye care professional if you notice this in yourself or family members.
What Colours Can The Iris Be?
The iris can range from the common brown and blue to the rarer purple, pink, and even black shades. Eye colour results from a combination of the amount of or lack of melanin in the iris and the reflection of light from the cornea, creating unique hues.
Brown is the most prevalent eye colour worldwide, found in approximately 55% to 79% of the global population.
Blue eyes occur in around 10% of the global population.
~10% of the global population.
~5% of the global population.
~3% of the global population.
Found in about 2% of the global population.
Less than 1% of the global population.
Less than 1% of the global population (typically patients with Albinism).
0.001% of the global population (Patients with no iris or Aniridia).
How Is Heterochromia Treated?
Healthcare providers don’t have a specific treatment for heterochromia. If your healthcare professional determines heterochromia is harmless, there is nothing you need to do for treatment. For some, coloured contacts may be the safest cosmetic option if you want both eyes to be the same colour. Talk to your eye care professional if you are interested in colour contact lenses. Contact lenses even if the contact lenses do not have any corrective power for your vision, should only be worn as prescribed, dispensed, and fitted by a qualified eye care professional.
You can get surgery for cosmetic purposes, though not very common or recommended. There are iris implant surgeries and keratopigmentation surgery that inserts pigmentation into the cornea. The American Academy of Ophthalmology issued a warning on the dangers of cosmetic eye colour changing surgical procedures on Jan 29, 20241.
If heterochromia is due to an underlying health condition, then it is important for quick diagnosis and treatment. For this reason, it’s important to see an eye care professional for a complete eye health examination.
Conclusion
Whether genetic or acquired, heterochromia serves as a reminder of the beauty in diversity. If you are interested in learning more, contact us today!
Dr. Patrick O’Brien, Optometrist
Dr. O’Brien has been with Mission Eye Care since 2009. With a strong foundation in both primary eye care and disease management, he continues to provide high quality eye health care to our patients.
