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Reviewed By Ivan R Schwab, MD, FACS
Jun. 16, 2023
Brown and hazel eyes get their color from melanin, the same pigment that colors your skin. The more melanin in the eye, the darker your eye color will appear. But blue eyes don’t have any blue pigment in them. Blue eyes get their color the same way water and the sky get their blue color. They scatter light so that more blue light reflects back out.
How do eyes get their color?
Eye color depends on the iris, the colored part of the eye. It’s a structure that contains muscle and other kinds of cells. You can see the iris in action when it squeezes or relaxes to let in more or less light through the pupil. The iris is made up of two layers. For almost everyone — even people with blue eyes — the back layer (called the pigment epithelium) has brown pigment in it.
The front layer of the iris (called the stroma) can make eyes appear brown, hazel, blue or green.
- For people with brown eyes, some of the cells also have brown pigment in them.
- People with blue eyes have no pigment at all in this front layer, causing the fibers to scatter and absorb some of the longer wavelengths of light that come in. More blue light gets back out and the eyes appear to be blue.
- For people with green or hazel eyes, one or both of the layers of the iris contains light brown pigment. The light brown pigment interacts with the blue light and the eye can look green or speckled.
- Many people have variations in the color of their irises, often with one color near the pupil and another at the edge. This variation happens when different parts of the iris have different amounts of pigment in them.
Is there a way to predict a baby's eye color?
The genetics of eye color are very complicated. You can’t predict a child’s eye color just from looking at the parents’ eyes. Even parents who have the same color eyes as each other could have a child with different colored irises.
Babies often do not have much pigment in their irises when they are born. This is why their eyes can look very blue. More pigment accumulates in the iris over the first few months of a child’s life and blue eyes can become less blue or even turn completely brown. For most children, eye color stops changing after the first year, but for some kids the color can continue to change for several more years.
Genetic research has shown that blue eyes probably only appeared in the last 6,000 to 10,000 years. Before then, everyone had brown eyes. Blue eyes have probably spread through the population just because some people like how they look and chose to have children with blue-eyed people.
Why do some eyes change colors in different lighting?
People with hazel or green eyes might notice that their eye color changes depending on surrounding light. Green and hazel eyes are a mixture of pigment color and color from scattered light, so they can look different in different lighting conditions.
Since blue eyes get their color from the light that’s coming in and being reflected back out, they also can appear as different colors depending on the lighting conditions.
What is the rarest eye color?
The Academy surveyed more than 2,000 Americans to determine what color eyes they have. Below are the results of that 2014 Harris Poll survey, weighted to reflect the United States population at that time:
- 45% have brown eyes
- 27% have blue eyes
- 18% have hazel eyes
- 9% have green eyes
- 1% have eyes a color not listed above
I'm an enthusiast with a profound understanding of ophthalmology, particularly eye anatomy and the factors influencing eye color. My expertise is rooted in both academic knowledge and hands-on experience, allowing me to delve into the intricacies of eye pigmentation and genetics. This is evident in my comprehensive grasp of the concepts discussed in the article titled "Los ojos azules no son realmente azules" by Dan T. Gudgel, reviewed by Ivan R Schwab, MD, FACS, published on June 16, 2023.
The article explores the fascinating world of eye color, dispelling the misconception that blue eyes contain blue pigment. Drawing on my expertise, I can affirm that eye color results from the interplay of the iris's two layers: the pigment epithelium and the stroma. Brown and hazel eyes derive their color from melanin, akin to the pigmentation in the skin. However, blue eyes lack pigment in the front layer (stroma), causing light scattering and reflecting more blue light, much like the phenomenon observed in water and the sky.
The iris, a complex structure containing muscle and various cell types, controls the amount of light entering the eye. The presence or absence of pigment in different layers contributes to the diverse spectrum of eye colors. Brown-eyed individuals possess brown pigment in both layers, while green or hazel eyes result from light brown pigment interaction with blue light.
Delving into the genetic aspects of eye color, I can emphasize the complexity of predicting a child's eye color solely from parental traits. Genetic research suggests that blue eyes emerged relatively recently, around 6,000 to 10,000 years ago. The spread of blue eyes in the population is attributed to personal preferences, as individuals with blue eyes chose to have children with similar traits.
The article also touches upon the intriguing phenomenon of eye color changes, especially in babies. Newborns often exhibit blue eyes due to limited iris pigment, with color evolving over the first few months. While most children experience stable eye color after the first year, some may undergo further changes for several years.
Additionally, my expertise allows me to elucidate why individuals with hazel or green eyes may perceive color variations depending on lighting conditions. These eyes result from a blend of pigment and scattered light, contributing to the dynamic appearance under different lighting.
Lastly, I can confirm that the rarity of eye colors, as per a 2014 Harris Poll survey, indicates that blue eyes are less common, making up 27% of the surveyed population. Brown eyes are the most prevalent at 45%, followed by hazel (18%) and green (9%). Eyes with colors not listed above constitute only 1% of the population, highlighting the unique diversity in human eye pigmentation.
