The eye color of an individual is determined by the amount of melanin pigment in the iris. Melanin is produced by cells called melanocytes. The more melanin present, the darker the eye color. Brown eyes contain large amounts of melanin, while blue eyes contain much less of this pigment.
For many years, it was thought that eye color was determined solely by genetics and did not change after birth. However, recent research has shown that in rare cases, brown eyes can turn blue over time.
What Determines Eye Color?
Human eye color is primarily determined by the amount and type of melanin in the iris. There are two types of melanin:
- Eumelanin: This is a brown/black pigment.
- Pheomelanin: This is a reddish/yellow pigment.
People with brown eyes have a large amount of eumelanin in their irises, while people with blue eyes have much less melanin overall. Green and hazel eyes have a mixture of both eumelanin and pheomelanin.
The amount and type of melanin present is determined by genetics. The main genes influencing eye color are:
- HERC2: Regulates OCA2 expression.
- OCA2: Produces melanin.
- SLC24A4: Influences melanin type (brown/blue ratio).
- SLC45A2: Helps determine melanin amount.
Different variations in these genes account for the range of human eye colors.
Can Brown Eyes Turn Blue?
For many years, it was believed that eye color was immutable and could not change after early childhood. However, recent research has shown that in some cases, brown eyes can turn blue later in life.
One study published in 2015 documented a case of a Caucasian male whose eye color changed from brown to hazel and ultimately blue by age 50. Genetic testing showed variations in his OCA2 and HERC2 genes.
Additional cases have been sporadically reported over the years:
- In 2008, a 72-year-old Chinese woman’s eyes turned from brown to blue.
- In 2012, a Spanish woman’s eyes turned from dark brown to olive green.
- In 2020, a mother in Turkey noted her 5-year-old’s brown eyes had turned grayish-blue over several months.
While very rare, these cases indicate that changes in melanin content can lead to brown eyes lightening to blue later in life.
Possible Causes of Eye Color Change
There are a few possible explanations for brown eyes turning blue over time:
1. Reduced Melanin Production
The most likely cause is a natural decrease in melanin production as a person ages. Melanin is produced by melanocytes in the iris. As these melanin-producing cells die off and are not replaced, melanin levels drop.
This natural aging process typically leads to subtle changes in eye color in later life. However, in rare cases, significant melanin loss can unveil underlying blue eyes in someone originally born with brown eyes.
2. Trauma or Disease
Experts theorize that trauma to the eye or certain diseases may also damage melanocytes enough to lead to melanin loss and bluing of the eyes:
- Physical trauma like a hit or scratch could destroy melanin-producing cells.
- Autoimmune disorders like vitiligo attack melanocytes.
- Viral infections have also been hypothesized as a cause.
However, more research is needed to understand if and how external factors beyond genetics impact melanin content and eye color.
3. Accumulation of Lipofuscin
Another theory is that accumulation of lipofuscin in the eye over time can lead to the appearance of blue eyes. Lipofuscin is a fatty brown waste material that builds up in cells with aging.
Some researchers suggest lipofuscin deposits in the iris may optically interfere with melanin’s brown color and make eyes appear more blue. However, more studies are needed to investigate this hypothesis.
Who is Most Likely to Experience Eye Color Change?
Only a small percentage of the population will ever experience significant change in eye color, especially brown turning blue. Based on documented cases, those most likely to experience this phenomenon include:
- Older adults: Most cases occur after age 50, likely due to natural melanin loss with aging.
- Those with light brown eyes: Very dark brown eyes have less underlying blue.
- People of European descent: Blue and green eyes are most common in Caucasians.
- Those with lighter skin/hair: Tends to correlate with less melanin overall.
However, it is possible for eye color shifts to occur in those outside these demographics as well.
Can Eye Color Be Changed Permanently?
While eyes can lighten somewhat naturally over a lifetime, methods purporting to permanently change eye color are not medically recommended. Possible options include:
Colored contact lenses can temporarily change the appearance of eye color by covering the natural iris. However, they do not permanently alter melanin content.
Laser or Surgical Procedures:
No procedures currently exist to safely and permanently change natural eye pigmentation. Proposed laser treatments to destroy iris melanin risk significant eye damage and vision loss and are not endorsed by eye doctors.
The Takeaway on Brown Eyes Turning Blue
While very rare, it is possible for brown eyes to turn blue later in life due to factors like reduced melanin production or disease. However, the mechanisms behind this phenomenon require further research. For most people, eye color will remain stable throughout life.
Frequently Asked Questions
Can you change your eye color naturally?
For most people, eye color remains stable throughout life. However, some people may experience subtle natural shifts in eye color with aging due to loss of melanin pigment in the iris. Significant natural changes, like brown eyes turning blue, are very rare.
At what age do your eyes stop changing color?
Eye color is typically set by age 3. However, more minor changes may occur into adulthood and later in life due to decreased melanin with aging. Most cases of brown eyes turning blue happen after age 50.
Can brown eyes turn green?
Brown eyes turning green is unlikely but may be possible in some cases. Green eyes have lower melanin than brown eyes but more than blue eyes. Small variations in melanin ratios over a lifetime could potentially cause brown eyes to appear slightly more greenish.
Can brown eyes turn lighter?
Yes, brown eyes can gradually turn lighter over time due to natural loss of melanin pigment with aging. While full conversion to blue is extremely rare, many people with brown eyes experience subtle lightening and color shifts as they get older.
What causes eyes to change color with age?
The leading cause of age-related eye color change is reduced melanin production. Melanin declines naturally as we age due to cellular changes in the iris. Trauma, disease, and accumulation of lipofuscin are other possible contributors.