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Gray Eyes: Causes, Pros, and Cons

Having gray eyes is one of the rarest physical conditions in the human race. The color is caused by the front layer of the iris having less melanin than the back layer. Women with gray eyes tend to have a blue shade of gray, while men usually have a green shade of gray.

woman with gray eyes

How Does Someone Get Gray Eyes 

More than eight genes influence the color of the eyes, primarily regulating the quantity and quality of the iris melanin pigment. Those with grey eyes have little melanin on their irises but a lot of collagen that reflects light and makes the iris look gray.

Gray eyes refer to an iris that contains a shade of gray color. It is such a rare occurrence that only about 3 percent of the world’s population has gray eyes

Shades of Gray

Individuals with varying intensity can have grey eyes, resulting in smoke color, dark grey, almost hazel, bluish-grey, or greenish-grey eyes. A blue shade of gray is typical in women, while green is common in men. 

The hue of the grey eye may change depending on the mood, surrounding lighting, the weather, medication taken or what you wear. 

Causes of Gray Eyes

When eyes have a dark iris, it means your eyes have plenty of melanin. If you have gray eyes, the front layer of the iris has less melanin than the back layer, so external light passes through, and the back layer reflects it. 

The reflection causes a cloud in the stroma, which may manifest as a gray, blue, or green iris. The stroma between the two layers of the iris contains collagen that reflects light. It is the melanin pigmentation that determines eye color. 

Risks Associated with Gray Eyes

Gray-colored eyes can put some people more at risk because of light sensitivity and other characteristics associated with gray eyes. People with gray eyes can be:

  • Sensitive to light
  • More prone to macular melanoma
  • More prone to skin cancer

Light Sensitivity

Melanin pigment in the eye reduces the eye’s sensitivity to light. People with light-colored eyes cannot withstand harsh lighting. They squint, lose focus and may even experience pain when exposed to bright light, a condition called photophobia.

The condition has temporary effects, and you can mitigate it by avoiding bright light if you have gray eyes. It does not cause loss of vision, even in the long term.

Ocular Melanoma

Ocular melanoma is an eye cancer that affects the uvea layer of the eye. You will get cancer after exposure to UV rays, and people with light eyes are more prone than those with darker eyes. It is rare and has an annual 0.0006 percent chance of occurrence.

People with lighter eyes should take precautionary measures like wearing wide-brimmed hats and polarized sunglasses to minimize UV exposure. Melanoma can result in loss of vision or the spreading of cancer cells.

Skin Cancer

In most situations, having gray eyes is accompanied by having fair skin because of lesser than usual melanin pigment. Melanin pigment offers protection from the sun’s UV rays. 

Fair skin can redden, get freckles and sunburns easily, and is prone to skin cancer. This does not mean that people with a dark complexion cannot get skin cancer. 

Benefits Associated with Gray Eyes

There are benefits to having gray eyes. 

Less Sensitivity to Pain

People with gray eyes experience less pain than those with darker eyes. The pain relief extends to overwhelmingly painful situations like labor during birth. 

More Tolerant 

Someone with gray eyes is also less sensitive to medicine and alcohol, which means they can take a bit more than people with other dark eyes before becoming intoxicated. 

Strong Cornea

People with gray eyes have more collagen than usual in the cornea’s stroma. Usually, collagen strengthens the cornea while boosting the curvature, especially where the cornea layers are thin. This fortification maintains the shape of the eye. 

More Competitive

According to a study of North Europeans, people with a lighter shade of iris, such as gray, are more competitive than their contemporaries with darker-colored irises.

Benefits of Gray Eyes and Light Eyes

There are some benefits to having gray eyes, or light eyes. 

Less Risk of Vitiligo

Vitiligo is less likely to affect people with gray and lighter eyes. That also means gray eye-colored people are also less likely to contract other autoimmune diseases accompanying vitiligo, such as systemic lupus, type 1 diabetes and Crohn’s disease.  

Calm Personality

People perceive gray-eyed people to be calm and intelligent. The ancient Greeks claimed that the goddess Athena had gray eyes and associated them with wisdom. A poll found that men consider that women with gray eyes are more attractive, mainly because they are rare. 

Changing Colors 

Sometimes, newborns are born with gray eyes and develop darker pigmentation as they grow. The hue may change depending on mood and lighting for those with permanently gray eyes. They, therefore, get to enjoy having varying eye colors.


  1. Eye Color and its Inheritance. (Retrieved April 2022). Cornell University.

  2. The World’s Population By Eye Color. (October 2020). WorldAtlas.

  3. Ocular melanoma. (2018). National Organization of Rare Disorders.

  4. Specific Eye Conditions, Corresponding Impact on Vision, And Related Educational Considerations. (February 2016). Texas School for the Blind and Visually Impaired.

  5. Fact or fiction: are blue eyes more sensitive to light? (October 2014). Penn State University.

  6. Myths of Human Genetics. (December 2011). The University of Delaware.

  7. Eye color predicts disagreeableness in North Europeans: support in favor of Frost (2006). (2010). Griffith University.

  8. Skin Color Adaptation. Palomar College.

Last Updated May 16, 2022

Note: This page should not serve as a substitute for professional medical advice from a doctor or specialist. Please review our about page for more information.

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