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What Causes Grey Eyes & How Common They Are

What Causes Grey Eyes & How Common They Are

Grey eyes are one of the most unique eye colors in the world. Their hues range from pale to smoky and steely to grey-blue and grey-green. With captivating shades across the spectrum, grey is one of the least common but perhaps the most enchanting of all eye colors.

When we talk about eye color, we’re referring to the iris — the colored portion of the eye surrounding the dark black center (pupil). While there may be varying shades of a specific hue, no two people have the same exact eye color.

Read on to learn more about grey eyes, how many people have them, and the factors responsible for their appearance.

A closeup of a grey eye

What Causes Grey Eyes?

Grey eye color, and eye color in general, is largely influenced by genetics. But it’s also the result of substances in the body called melanin and collagen.

Melanin in Grey Eyes

Melanin is a pigment that determines the color of your hair, skin, and eyes. The more melanin you have, the darker your features generally are. Eye color results from the amount, type, and distribution of melanin in the iris, which has two distinct layers.

The front layer of the iris (the stroma) is where your eye color appears. The back layer (pigment epithelium) contains brown pigment. In all eye colors, melanin is typically present in both layers of the iris — just in different amounts.

Most eye colors have a fair amount of melanin in the back layer of the iris.

When it comes to the front layer, grey and other light-colored eyes have little to no melanin, while darker eyes (such as brown) have more. This helps create the eye color you see when looking at the iris.

Collagen in the Eyes

The front layer of the iris also contains collagen. Collagen is a protein in the body that acts as a scaffolding system, providing structure to various tissues.

Light reflects off the collagen fibers in the front layer, producing a haze or cloud. This cloud helps give a grey, green, or blue color to a light-colored iris.

Grey eyes tend to have more collagen than other eye colors, lending to their unique appearance.

Other Factors That Influence Eye Color

Lighting, eye makeup, and clothing can affect the appearance of grey eyes and other eye colors. This is due to an optical illusion rather than an actual change in color.

Changes in the size of your pupil, such as when it dilates (gets bigger), can also give the illusion of a change in eye color. Your pupils may dilate if your mood changes, you move to a more dimly lit environment, or take certain medications (among other causes).

But aging, certain medications, and some health conditions can alter your eye color. Be sure to consult your eye doctor if you notice a change in your eye color. It may be caused by an eye condition or other concern that needs to be checked out.


How Rare Are Grey Eyes?

Grey is one of the rarest eye colors in the world. While not as uncommon as other hues, such as red or violet eyes, grey eyes are still rarer than colors like brown, blue, and hazel.

This eye color is more prevalent in certain parts of the world, particularly in the Middle East, South Asia, and Central Asia. Additionally, the Algerian Shawia people in Northwestern Africa have a higher incidence of grey eyes compared to other populations.


What Percentage of People Have Grey Eyes?

Estimating the exact number of people with grey eye color can be challenging. But experts believe that about 3% of the world’s population has grey eyes.

Here’s how grey stacks up to other eye colors across the globe:

  • Brown eyes – 70% to 80%
  • Blue eyes – 8% to 10%
  • Hazel eyes – 5%
  • Amber eyes – 5%
  • Grey eyes – 3%
  • Green eyes – 2%

A closeup of a woman's face with blonde hair and grey eyes

What Causes Eyes to Turn Grey?

As mentioned above, changes in eye color can sometimes be associated with an underlying medical condition or certain medications. Parts of the iris may be affected, or the entire iris may change color, depending on the condition and its effects. Cataracts, for example, may give the eyes a greyish appearance.

In other cases, the white of the eye (the sclera) may become discolored and take on a bluish-grey tint. This can be due to factors such as:

  • The prolonged use of some medications
  • An iron deficiency or anemia
  • Thinning of the sclera (that exposes an underlying structure called the choroid)
  • Certain bone or other connective tissue conditions present at birth

It’s important to note that the whites of the eyes may turn other colors, which can also indicate underlying health concerns. Schedule an exam with your eye doctor right away if you notice any change in your eyes, eye color, or vision.


What Are Grey Spots on the White of the Eye?

Grey spots on the whites of the eyes can be concerning, especially if they appear suddenly or without an obvious cause. Various conditions and factors can cause these spots to develop, including:

  • Age-related factors
  • Eye trauma or injury
  • Eye dryness or irritation
  • Bacterial, viral, or fungal infections
  • Certain eye or health conditions that are present at birth or acquired later

While grey spots on the white of the eye may be benign, they could also indicate something serious. Any type of eye discoloration warrants a trip to your eye doctor’s office.


Protect Your Eyes and Vision

Grey eyes and other light-colored eyes are often more sensitive to sunlight. People with light eyes may also have a higher risk of developing some eye diseases and health concerns. You can help keep your eyes safe in the sun by wearing sunglasses that provide 100% UV protection.

A woman outside smiling and wearing sunglasses

It’s also essential to schedule annual eye exams with your eye doctor. Yearly exams allow them to detect eye and vision problems early, which can help preserve your eyesight and eye health for years to come.

Whether you need prescription eyeglasses, reading glasses, or anything in between, we’ve got you covered!