It’s not uncommon for people with brown eyes to notice their eye color changing over time. Often, brown eyes can take on flecks or streaks of green, yellow, or orange, transforming into a hazel color. This occurs naturally in many people, especially as they age. There are a few different reasons why brown eyes may turn hazel.
Melanin Levels
The main factor that determines eye color is melanin, which is the pigment that gives color to the iris. People with brown eyes have a high concentration of melanin in their irises. Over time, melanin levels can fluctuate and decrease naturally. As melanin declines, it reveals other pigments that were hidden underneath, changing the overall eye color. This allows shades of green, amber, or orange to show through, turning brown eyes hazel.
Melanin Production
Melanin is produced by melanocytes, which are specialized cells in the colored part of the eye called the iris. Melanocytes contain granules of melanin called melanosomes. In brown eyes, there is a high level of melanosomes. As we get older, melanocytes can slow down melanin production. With less melanin in the iris, other colors become visible. This natural decrease in melanin is one reason brown eyes turn hazel later in life.
Factors Affecting Melanin
Many factors can impact melanin levels and distribution in the body. Here are some that may influence eye color:
- Age – Melanin levels naturally fluctuate and often decrease with age.
- Genetics – Genes regulate melanin production. Changing genes means changing melanin.
- Diet – Vitamin and mineral intake may impact melanogenesis.
- Sun exposure – Exposure to UV light can reduce melanin over time.
- Oxidative stress – This damages melanocytes, reducing melanin.
As these factors change the amount of melanin in the colored part of the eye, brown eyes can gradually turn hazel.
Rayleigh Scattering
Another factor that can contribute to eyes changing from brown to hazel is a phenomenon called Rayleigh scattering. This is the scattering of light by particles that are smaller than the wavelengths of visible light.
How Rayleigh Scattering Affects Eye Color
In the eye, Rayleigh scattering occurs in the stroma – the dense connective tissue in front of the iris. The stroma contains collagen fibers that disperse light. As we age, the collagen fibers in the stroma clump together and become thicker. This affects how light is scattered. More blue wavelengths are scattered, making the stroma appear more yellow. The yellow stroma can mix with the brown melanin in the iris, producing hazel eyes.
Examples of Rayleigh Scattering
Some other natural examples of Rayleigh scattering are:
- The blue sky – Shorter blue light waves are scattered by the atmosphere
- Red sunsets – The sun’s red wavelengths pass straight through.
- Cloudy or polluted days – More light is scattered, making the sky appear white.
This same principle applies in the eye. As the stroma changes with age, Rayleigh scattering alters, allowing new colors to appear.
Changes in Iris Structure
In addition to chemical changes like melanin levels, structural changes in the iris can also turn brown eyes hazel.
Iris Freckles
With age, some people develop small freckles or spotting on their irises. These freckles are concentrated areas of melanin pigment. When they develop in brown eyes, they can make parts of the iris appear darker brown or orange-brown. This contributes an accent color such as amber or orange to otherwise brown eyes, creating a hazel effect.
Fiber Changes
The iris contains collagenous connective tissue fibers, which give structure to the eye. Over time, these fibers may clump or degrade. As the fiber network changes, it can unmask hidden colors in the iris. This may open up areas of green or yellow-green that turn brown irises hazel.
Injuries and Medical Conditions
Sometimes, changes to the structure or chemistry of the eye due to injury or disease can lead to brown eyes turning hazel.
Eye Injuries
Physical trauma to the eye area may damage melanocytes and cause melanin levels to decrease. If the injury only affects part of the iris, it could change the color in just that area to a lighter brown, green, or amber shade. This can make the eye appear hazel.
Medical Conditions
Certain medical conditions are associated with acquired heterochromia, meaning the eyes become two different colors. These include:
- Horner’s syndrome – A disruption of nerves that control the iris.
- Fuch’s heterochromic iridocyclitis – Inflammation of the iris.
- Pigmentary glaucoma – A type of glaucoma that affects melanin.
In these conditions, melanin content can be altered in one eye but not the other. If it affects an originally brown eye, it can turn it hazel while the other eye remains brown.
Is the Color Change Permanent?
For many people, the shift from brown to hazel is a permanent change. The natural decrease in melanin levels and increased Rayleigh scattering that occurs with age is not reversible. Structural changes like iris freckling and fiber changes may also be permanent.
However, if the hazel color is caused by a temporary factor like an injury or medication use, it may be possible for the eyes to revert back to their original brown. Talk to an ophthalmologist if you notice a sudden color change to determine the cause.
Will My Future Children Have Hazel Eyes?
If your eyes turned from brown to hazel later in life due to natural aging processes, it will not affect the eye color of future children. The genes you pass on are not changed by aging.
The inheritance of eye color is complex, involving multiple genes. If you have brown eyes and your children were born with brown eyes, they likely inherited brown eye genes from both you and your partner. For this reason, your later hazel eyes will not lead to hazel-eyed children. The child would need to inherit hazel eye genes from one of the parents.
However, if your eye color change is due to a specific genetic mutation rather than aging processes, it could potentially be passed to offspring. Consult a genetic counselor if you have concerns.
Can Diet or Lifestyle Changes Reverse Hazel Eyes Back to Brown?
While certain lifestyle factors like sun exposure and diet can impact melanin levels, it is unlikely that any natural remedies can reverse hazel eyes back to the original brown color.
The shift that occurs as brown eyes turn hazel is largely due to age-related changes in melanin and collagen fibers that cannot be reversed through diet or supplements. Any products that claim to change your natural eye color should be approached with caution.
However, protecting your eyes from UV light with sunglasses and eating a healthy diet rich in vitamins A, C, and E may help slow any further color changes by supporting eye health. But these measures cannot undo changes that have already occurred.
Should I Be Concerned About Hazel Eyes?
There is no medical reason to be concerned if your naturally brown eyes have turned hazel. This is a common, benign occurrence. However, see an ophthalmologist promptly if you experience:
- A sudden change in only one eye’s color
- Very uneven color distribution in the two eyes
- Pain, vision issues, or redness along with the color change
- AHazel eye color spreading from the outside edge of the iris inward
These may indicate a medical condition like glaucoma or Horner’s syndrome. But gradual, evenly distributed hazel coloring, especially in both eyes, is normal and no cause for worry. Enjoy your new eye color!
Conclusion
Brown eyes turning hazel commonly occurs from natural processes like decreasing melanin, increased Rayleigh scattering, iris freckling, and collagen changes. This explains why many people begin to notice hazel flecks or streaks in their brown eyes by middle age or later in life. The hazel color is permanent in most cases. While you can protect your eyes from further changes through UV protection and diet, the shift from brown to hazel cannot be reversed once it occurs. As long as the change happens evenly in both eyes and causes no other symptoms, developing hazel eyes is perfectly normal.
