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Eye color and image -

Eye color is generally considered a defining characteristic. When asked to describe a person, we often refer to their eye color, as well as their hair color and stature.

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Is it permanent? -

This would suggest that eye color is permanent; that it does not change over time. And, indeed, for the most part that is true.

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Infant eye color -

However, there are circumstances in which our eye color can change. In fact, for infants under one year of age, eye color change is actually quite common.

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Blue to brown -

Have you ever met a baby who was born with bright blue eyes, only to see the same baby a year later and find they have deep brown peepers?

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Quite common -

You’re probably not the only one. Although not much research has been done into infant eye color change, it is thought to be reasonably common.

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Common understanding -

In maternity wards, you’ll often hear new parents talking about how their baby was born with blue eyes, but how “that will probably change.”

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Hypothesizing - We do not have a definite answer as to why babies’ eye color changes in the months after birth. However, it may have to do with the quantity of pigment in the eyes.

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The role of melanin -

The main pigment in our eyes is melanin, which offers protection from sun damage in the same way it does in the skin.

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Built up over time -

As a general rule, brown eyes have higher levels of melanin than blue eyes, and it is thought that eye color may change as levels of melanin build up over time.

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Remaining unknown - Exactly why some infants’ eyes appear to express more melanin over time than others is still not clear.

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Classic combination -

Almost certainly there is a combination of genetic and environmental factors at play, but we do not currently have that data available for the general population.

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Adult eye color change -

Although eye color change later in life is much less common, it is not in fact impossible. The main reasons for eye color change in adults are injury, infection, and sun damage.

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Famous case - Perhaps the most famous example of eye color change due to injury was David Bowie. Famously, the musician had one dark eye and the other pale blue. 

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Aniscoria -

Bowie had a condition called anisocoria, which was caused by a blow to the head that left his pupil permanently dilated.

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Iris color change -

In Bowie’s case, it was not actually the iris that changed color. However, there are also injuries that can cause this sort of change.

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Iris color change -

If, for example, you sustain an injury that causes a lot of blood to leak into the eye, this can stain parts of the eye and cause the iris itself to change color.

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Change as a result of infection - More common, though, is eye color change as a result of an infection. There are certain infections that can cause the pigment in the eye to disappear. 

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Famous case -

A famous example of someone who has true heterochromia—two irises of different colors—as a result of infection is actress Mila Kunis.

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Mila Kunis and heterochromia -

Kunis has one brown eye and one green, thanks to an infection of the iris that destroyed some of the pigment.

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More unusual -

There are even some viruses not normally associated with the eyes that can thrive in the interior of the eye and affect pigmentation.

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Ebola case -

In one extremely rare case, there was an Ebola survivor whose eye color changed from blue to green, after the virus was cleared from the rest of his body but found to persist in his eye fluid.

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Iris flecks -

The overall eye color may also appear to change due to the emergence of small flecks in the iris (as opposed to a change that affects the whole iris).

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Brushfield spots -

For example, pale flecks known as Brushfield spots can appear in the irises of people with Down syndrome.

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Lisch nodules -

Dark flecks, also known as Lisch nodules, are a common sign of the genetic condition neurofibromatosis type 1.

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Freckles and moles -

Freckles and moles can also develop anywhere in the eye. As with freckles and moles on the skin, it is a good idea to stay on top of these.

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Keeping a close eye -

More often than not, they do not do anything and are benign. However, for some people they can grow into tumors and become very problematic.

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When to see a doctor - As a general rule, it is a good idea to see a doctor if you notice a dramatic change in eye color in anyone older than one year.

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All in all -

Adult eyes may appear to change color as their pupils dilate or they change their outfit, but an actual change in eye color may be a signal that something is wrong.

Sources: (BBC) (WebMD)

See more: Rare human body features you didn’t know exist

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