What determines the color of the human eye? Change in iris color

It often happens that a child is born with light eyes (light blue or light green), but over time they darken and become dark gray or even brown. Let's find out if this is normal? And in general, why do people have different eye colors?

The color of a person's skin, hair and eyes depends on the content of the melanin pigment. He absorbs ultraviolet rays and protects us from radiation damage. This is why light-skinned people burn faster in the sun than dark-skinned people: their skin has less pigment. The color of the iris also depends on the content of melanin, as well as on the density of the fibers of the iris.

The main eye colors are blue, indigo, gray, green, amber, marsh (hazel) and brown.

Those with blue and blue eyes have the lowest melanin content in the iris, while those with brown eyes have the highest. The notorious black eyes are eyes dark brown color. Albinos have red eyes, this is due to the fact that there is no melanin in their body at all, so the color of the iris is determined by the color blood vessels.

Eye color (or rather, the amount of melanin) is a genetically determined trait. Dark eye color is dominant, and light eye color is recessive, therefore dark eyes occur more often. The most common eye color in the world is brown, and the rarest is green. Eye color also depends on the region of residence - different nations different frequency distribution of certain eye colors.

Let's say, if among the Russians brown eyes About 30% of people have it, then among Ukrainians it is already 50%, and among Latin Americans this figure reaches 80%. Of course, this is a simplified scheme, inheritance of eye color is much more complicated, but in any case, a brown-eyed child cannot be born to light-eyed parents (but the opposite is quite possible). You can determine what color a child's eyes will be based on the eye color of his parents. But in most cases, several options are possible with different probabilities, so the most accurate way to predict end result only possible for a child of two blue-eyed parents.

But even if a child was born with light eyes, this is not necessarily forever. Over time, newborns' eye color may change. This is due to the fact that special cells (melanocytes) do not immediately begin to produce melanin, and the accumulation of pigment in the body goes gradually. A child born with gray eyes may well become brown-eyed over time. The eyes can finally accept normal color and in six months, and in a year, and even in two or three years.

It is worth remembering that eyes can change from light to dark, but from dark to light - not (unless a malfunction occurred in the child’s body that disrupted the production of melanin).

It also happens that the eyes have different color: one is colored stronger, and the second is weaker. This phenomenon is called heterochromia, and it is associated with a relative excess or deficiency of melanin. Partial (sectoral) heterochromia also occurs, when areas of the iris of one eye are colored differently, but this is a rarer phenomenon than complete heterochromia. Heterochromia can be caused by various reasons. Sometimes, apart from changing the color of the iris, it does not manifest itself in any way, and sometimes it can be accompanied by complications, including cataracts. Therefore, people with heterochromia need to be regularly monitored by an ophthalmologist.

From school course In biology, we know how a child’s eye color is genetically determined, we know that brown color dominates blue and it happens that a person has eyes of different colors. We will tell you facts you didn't know. For example, at what age does eye color develop and why does our iris have one color or another?

Fact 1: all people are born with light eyes

Please note that all newborn babies have blue-gray eyes. Ophthalmologists explain this very simply - babies have no pigment in the iris. There are exceptions only in the countries of East, Southeast and South Asia. There, children's irises are already saturated with pigment.

Fact 2: We acquire our final eye color in adolescence

The color of the iris changes and forms by 3-6 months of a child’s life, when melanocytes accumulate in the iris. The final eye color in humans is established by the age of 10-12 years.

Fact 3: brown eyes are blue eyes

Brown is the most common eye color on the planet. But ophthalmologists say that brown eyes are actually blue under the brown pigment. This is a consequence of a genetic mutation. The outer layer of the iris contains large number melanin, resulting in the absorption of both high-frequency and low-frequency light. Reflected light results in a brown (brown) color.

Exists laser procedure, which allows you to remove pigment and make your eyes blue. It is impossible to return the previous color after the procedure.

Fact 4: in ancient times everyone was brown-eyed

Researchers have found that 10 thousand years ago, all inhabitants of the planet had brown eyes. Later, a genetic mutation appeared in the HERC2 gene, whose carriers decreased the production of melanin in the iris. This first led to the appearance blue color. This fact was established by a group of scientists at the University of Copenhagen led by Associate Professor Hans Eiberg in 2008.

Fact 5: a little about heterochromia

This is what is called the different color of the iris of the right and left eyes or the unequal color of different parts of the iris of one eye. This feature is explained by the fact of excess or deficiency of melanin due to diseases, injuries, and genetic mutations. With absolute heterochromia, a person has two different colors of the iris. One eye may be blue, the other - brown. There are 1% of people on the planet with such an unusual deviation.

Fact 6: green is the most rare color eye

1.6% of people on the planet have green eyes; it is the rarest, as it is eradicated in the family by the dominant brown gene. Green color is formed like this. The outer layer of the iris contains an unusual light brown or yellow pigment called lipofuscin. In sum with the resulting blue or blue turns out green. Purely green eye is extremely rare: the color of the iris is usually uneven, and this leads to the appearance of numerous shades. Most often, green eye color occurs in those whose genotype is dominated by the gene responsible for red hair color. Swiss and Israeli scientists came to these conclusions. These findings are indirectly confirmed by the high prevalence of green eyes among red-haired people. The results of the study are published in the section " Genetic nature» portal Nature.Com.

Fact 7: a little about other colors of the iris

Black the eye is similar in structure to brown. But the concentration of melanin in the iris is so high that the light falling on it is virtually completely absorbed. Black eye color is most common among members of the Mongoloid race in East, Southeast and South Asia. In these regions, the iris of newborn children is already saturated with melanin.

Blue The eye is the result of light scattering in the stroma (the main part of the cornea). The lower the density of the stroma, the more saturated blue.

Blue eyes, unlike blue, is explained more high density stroma. The higher the fiber density, the lighter color. As we all remember, this beautiful color scheme was partly the reason for the formation of fascist ideology. After all, according to scientists, 75% of the indigenous inhabitants of Germany have blue eyes. No other country in the world has such concentration blue eyed people.

Walnut color is a combination of brown (hazel), blue or light blue. And it can take on different shades depending on the lighting.

Gray the eye is similar to blue, while the density of the fibers of the outer layer is higher. If the density is not so high, the eye color will be gray-blue. Gray eye color is most common among residents of Northern and Eastern Europe, in individual regions North-West Africa, as well as among residents of Pakistan, Iran and Afghanistan.

Yellow the eye is extremely rare. It is formed due to the content of lipofuscin pigment (lipochrome) in the vessels of the iris. But in most cases, the fact of this eye color is explained by the presence of kidney diseases.

Fact 8: Albinos can have both red and purple eyes

The most unusual and interesting color eye, red, usually found in albinos. Due to the lack of melanin, the iris of albinos is transparent and appears red due to the blood vessels. In some cases, red, mixing with the blue color of the stroma, gives purple eye. However, such deviations occur in a very small percentage of people.

Prepared using materials: ailas.com.ua, medhome.info, glaza.by, medbooking.com, nature.сom, nfoniac.ru

It is very interesting to know what determines eye color. After all, the variety of colors of human eyes amazes the imagination and makes you wonder how it arose in nature.
What is commonly called “eye color” is nothing more than the color of the iris; the pigment cells contained in it give the eye its color: more pigment means darker color and vice versa.

What does eye color depend on and what factors influence it?

What determines the color of a person's eyes?

Albinos lack melanin, so their eyes appear reddish (blood vessels are visible through the translucent iris).

Scientists have discovered that people have different densities of the fibers that make up the iris.

This feature also affects the color of the eye. The more densely arranged the fibers that form the iris, the lighter its shade. The back layer of the iris is always dark, even in light-eyed people.

The blue color of the eyes is explained by the low content of melanin and the low density of the fibers of the iris.

Blue colored eyes mean that the fibers that make up the iris are denser. Their color can be close to white or gray.

In gray eyes, the fibers in the iris are even denser than in previous cases. The gray-blue tint of the eyes is formed due to the fact that this density is slightly less high.

Green eye color means that there is a small amount of melanin in the iris of their owner. It is known that green color is formed by mixing blue and yellow. The pigment lipofuscin is yellow in color and, superimposed on melanin, gives the eye a green color.

The amber or golden color is also formed due to high content in the iris there is a yellow pigment called lipofuscin.

Brown and black colors are obtained due to the high content of melanin in the iris. Black-eyed people have so much of it that the iris completely absorbs the color falling on it.

The color of the iris is acquired by a child from his father and mother, and the genetics of eye color are difficult to predict. There are thousands of color combinations for children and parents.

We all remember from school textbooks that the genes responsible for dark color, are dominant. The traits that are determined by them always “win” over those traits that are encoded by the genes responsible for a light shade.

However, all this does not mean that brown-eyed men and women will necessarily have brown-eyed children. Such a couple may also have a blue-eyed child if one of the grandparents has a different eye color. The baby may inherit a recessive gene from one of the parents.

Perception of color by the eye

The eye can be compared to a camera, because it also has its own light-sensitive layer - the retina. Nerve cells The retinas perceive reflected light and transmit sensations to the brain.

An image of the surrounding world appears in a person’s mind due to the processing of signals sent to the brain by eye cells – rods and cones. The former come into operation at dusk, the latter are responsible for the perception of color.

There is no objective and pure perception of color for humans. This process is not only physical, but also psychological. Perception is always influenced various factors: background, environment, shape of the object. For example, if a yellow object is placed against an orange background, it will appear cooler, greenish.

Under different lighting conditions, a blue object may appear either black or purple. In the dark, all objects appear black.

Thus, the color of things is not a constant and integral property of them, like, for example, shape and weight. In addition, the perception of color is affected by the individual characteristics of a person: age, eye health, emotional state.

It is almost impossible to see the color of an object in its “pure” form, but the most “correct” idea of ​​color can be obtained by looking at the object in daylight, without the bright sun.

Dependence on blood type

Ever since humanity became aware of the existence of blood groups, people have wondered whether there is a connection between blood type and other characteristics of a person ( appearance, health, character).

You may have come across statements that among carriers of the first and second blood groups, the majority are blue-eyed blonds, representatives of the third group are dark-skinned and black-eyed, and the fourth group is mixed.

Such hypotheses have not received scientific confirmation. The fact is that the genes that determine blood type and the genes responsible for eye color are not related to each other; they are located on different chromosomes. They cannot interlock with each other during the process of inheritance.

In addition, having a certain blood type does not directly depend on race or ethnicity, although blood groups are indeed distributed unevenly among different nationalities.

For example, 8 out of 10 American Indians have the first blood type, and among residents of northern Europe the second group is most common.

However, there are no distinctive external features in people with a specific blood type or Rh factor. Therefore, it is impossible to predict eye color based on a person's blood type. It is not even possible to calculate the probability that a person with a particular eye color will have a particular blood type.

Influence of a person's nationality

We easily notice a person of a different nationality due to their special appearance features, and eye color is not the last place in the list of such features. Most of the world's population has dark skin and black or brown eyes.

The appearance of Europeans is very diverse: they can have blue eyes, brown, green, and the inhabitants of the northern and Eastern Europe on average lighter.

The rarest eye color is green; only 2% of people have green eyes. Green-eyed people found among the Western Slavs, as well as some eastern peoples.

There are quite a lot of them among the Germans and Swedes. By the way, there are an unusually large number of green-eyed and blue-eyed people in Iceland - 80% of the population. In Turkey, only 20% of people have green eyes.

The most common eye color on Earth is brown, because its carriers are the vast majority of residents of India and China. The prevalence of brown color is also explained by the fact that it is the most “useful” color of the iris: dark eyes are not afraid of the bright sun. The peoples of the north, who have to observe the blinding glare of the snow, also have dark eyes.

About half of Russians have gray or brown eyes, blue and blue are less common (about 20%). In the northern part of the country, gray-green eye shades are common.

Useful video on the topic

Color change options

The eye color of adults can change under the influence of a wide variety of factors. There is even such a thing as “chameleon eyes.” Their color is difficult to determine, as it constantly changes under the influence of lighting and surroundings.

There are several reasons why a person’s eye color changes:

1. Age-related changes. It has been noticed that eye color can change as in childhood(until two or three years it is unstable), and in old age. In older people, the pigment begins to be produced in less volume, and the eyes may become a little lighter. For some, on the contrary, they darken due to the fact that the iris loses its transparency.
2. Changes in time of day. Eyes change color throughout the day. Of course, this phenomenon has nothing to do with pigmentation; it has to do with our perception of color, which can be influenced by lighting and environment. Moreover, in response to bright lighting the pupil narrows and the eye appears lighter. In the dark, the icon expands and even light eyes may appear almost black.
3. After tears. You may notice that after prolonged sobbing, a person acquires not only a red face, but also a brighter eye color than usual. Most likely, such changes are associated with the fact that the eye receives good hydration, the white becomes lighter, and the iris stands out more strongly against its background.
4. Disease. In some diseases (glaucoma, Horner's syndrome, Fuchs' dystrophy), changes in eye color may be observed.

Basic color change options

A few decades ago, change eye color, given by nature, it was impossible. To date, several ways have been invented to change the color of the iris.

If you are unhappy with the color of your eyes, want to experiment with your image, or want to eliminate a defect such as heterochromia, you have this opportunity.

Laser eye color correction

Laser technology for changing eye color was developed by Californian doctor Greg Homer. The doctor worked on his invention for ten years, and now twenty seconds are enough to change your eye color forever.

By the way, this procedure is irreversible. If you change your brown iris color to green, it will no longer be possible to return your original brown color back.

The essence of the procedure is that laser beam destroys the thin pigment layer of the eye. The cost of such an operation will be about five thousand dollars, and possible side effects have not yet been sufficiently studied. Ophthalmologists warn that this procedure may cause vision problems.

Implantation of artificial iris

This is the invention of the American surgeon Kenneth Rosenthal. He developed technology for changing eye color by installing it in the cornea silicone implants. This procedure may also be hazardous to health.

The first two months after the operation will be spent restoring vision, and in the future the chances of developing such serious illnesses, such as cataracts, glaucoma, corneal detachment. If you decide to change your eye color in this way, you risk going blind forever.

Rosenthal himself did not initially plan that the procedure he invented would be used for everyone. His job was to treat birth defects eye. However, some private US clinics still adopted this method and actively use it.

Special eye drops

A darker eye shade can be achieved by using certain types over a long period of time. eye drops. Such drops contain an analogue of the hormone prostaglandin F2a, which can affect the color of the iris.

This method of changing eye color can again be harmful to health, as it involves the use medical supplies not as prescribed by a doctor. Regular use of eye drops may cause nutritional problems eyeball.

Contact lenses

This is the most popular, inexpensive and safe way change eye color. However, it would not be a bad idea to consult an ophthalmologist who will help you choose lenses according to the characteristics of your eyes and your vision.

Lenses come in tint and color. The former change the eye color slightly, the latter will help change it radically.


If you have light eyes, any type of colored contact lenses will work, but for dark-eyed people it will be a little more difficult, because tint lenses will not be visible on dark eyes. Also, when purchasing tinted lenses, keep in mind that your natural eye color will mix with the color of the lens to create a new shade.

Properly selected makeup

The color you choose can slightly change your eye color. in the right way makeup. Using contrasting shades of eye shadow, you can highlight the natural color of your eyes, making it brighter and more saturated.

Cool shades of eyeshadow suit brown eyes, warm shades suit blue eyes, and gray eyes can be made slightly green or blue using appropriate shades of eye shadow.

Causes of heterochromia

People whose eyes are different colors look unusual. Heterochromia is the name of a phenomenon in which differences in eye color are observed. There are two varieties of this mutation: complete (the irises of the left and right eyes have different colors) and partial (colored spots or colored areas on the iris of one eye).

This feature is found not only in humans, but also in many animal species. For example, there are many “different eyes” among cats, among husky dogs, as well as horses and cows. It is usually combined with piebald or merle coloring. In humans, heterochromia occurs much less frequently than in animals (10 cases out of 1000).

Heterochromia does not affect health or vision in any way. This is just an abnormal pigmentation of the eye associated with an excess or lack of melanin. Most often, this feature is inherited from parents, but in in rare cases may be the result of injury or illness. It has been noticed that for some reason heterochromia occurs more often in women than in men.

If heterochromia is not caused by a disease or damage to the eye, it does not require treatment, and it is unlikely that it will be possible to change eye color forever. Can you hide heterochromia? contact lenses, but usually there is no urgent need for this. Many people consider people with eyes of different colors to be attractive, so their peculiarity is perceived not as ugliness, but as a kind of “highlight”.

It is worth noting that heterochromia is gradually becoming fashionable. Someone creates such a “mutation” artificially for themselves by putting on contact lenses, and teenagers often wonder how to get heterochromia.

Formation of eye color

It has been noticed that most newborns differ light color eye. The fact is that melanin appears in the body under the influence of light. Since there is no light in the mother’s womb, melanin is not yet released in the child’s body. Only after birth the amount of melanin in the baby’s eyes will gradually accumulate.

What determines the color of a child's eyes?

It is possible to determine the future color of a child’s eyes using special signs that are published in magazines and social networks. Predict it from one hundred percent certainty impossible, because not only mom and dad, but also grandparents contribute to the baby’s eye color.

There is no such specialist who could satisfy the curiosity of parents and determine in advance what the color of the eyes of an adult baby will be.

Child's color change

Parents are looking forward to the moment when their baby’s “final” eye color is established and they argue about which relative it was passed on from.

In the first days, it is too early to compare the shade of the baby’s eyes with the parent’s; heredity will manifest itself a little later. Most babies are born with light blue or light green eyes, and their shade may change during the first years of life.

On average, the first changes occur at about three months of age. A gray-eyed baby may eventually become green-eyed, and then brown-eyed. In some babies, eye color changes a few months after birth, six months, and a year.

Only at the age of two or three years does the baby acquire a “settled” eye color. There are, of course, exceptions to this rule - in some children, already in the first months of life, permanent color eye. They are usually dark-skinned and dark-eyed babies. It also happens that a baby is born with dark eyes.

It is also worth noting that a baby’s iris cannot become lighter over time, only darker. After two to three years the eye color is healthy little man cannot change dramatically, but small changes in their shade sometimes occur.

Let's find out what determines eye color

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4.12.2016 00:51

Eye color has great value in a girl's life, even if we don't think about it.
Very often, clothes, accessories and makeup are chosen directly to match the color of the eyes, not to mention the fact that, thanks to existing stereotypes, we, to some extent, make up our initial opinion about a person taking into account the color of his eyes.

The color of a person’s eyes, or more precisely the color of the iris, depends from 2 factors:
1. Density fibers iris.
2. Distribution of melanin pigment in the layers of the iris.
Melanin– a pigment that determines the color of human skin and hair. The more melanin, the darker the skin and hair. In the iris of the eye, melanin ranges from yellow to brown and black. In this case, the back layer of the iris is always black, with the exception of albinos.
Yellow, brown, black, where then do the blue and green eyes come from? Let's look into this phenomenon...

Blue eyes

The blue color is due to the low fiber density of the outer layer of the iris and the low melanin content. In this case, low-frequency light is absorbed by the back layer, and high-frequency light is reflected from it, so the eyes turn out blue. The lower the density of the fibers of the outer layer, the richer the blue color of the eyes.

Blue eyes

The blue color is obtained if the fibers of the outer layer of the iris are denser than in the case of blue eyes, and have a whitish or grayish color. The higher the fiber density, the lighter the color.

Blue eye color in babies
There is an opinion that all children are born blue-eyed, and then the color changes. This is a wrong opinion. In fact, many babies are actually born light-eyed, and subsequently, as melanin is actively produced, their eyes become darker and the final eye color is established by two to three years.

Gray it turns out similar to blue, only in this case the density of the fibers of the outer layer is even higher and their shade is closer to gray. If the fiber density is not so high, then the eye color will be gray-blue. In addition, the presence of melanin or other substances gives a small yellow or brownish impurity.

Green eyes

This eye color is most often attributed to witches and sorceresses, and therefore green-eyed girls are sometimes treated with suspicion. Only green eyes were obtained not due to witchcraft, but due to a small amount of melanin.
In green-eyed girls, yellow or light brown pigment is distributed in the outer layer of the iris. And as a result of scattering by blue or cyan, green is obtained. The color of the iris is usually uneven; there are a large number of different shades of green.

Amber

Amber eyes have a monotonous light brown color, sometimes with a yellowish-green or reddish tint. Their color can also be close to marsh or golden, which is due to the presence of lipofuscin pigment.

Brown eyes

Brown eye color results from the fact that outer layer The iris contains a lot of melanin, so it absorbs both high-frequency and low-frequency light, and the reflected light produces a brown color. The more melanin, the darker and richer the eye color. Brown eye color is the most common in the world.
Black eyes
Black eye color is essentially dark brown, but the concentration of melanin in the iris is so high that the light falling on it is almost completely absorbed.

Red eyes

Yes, there are such eyes, not only in the movies of vampires and ghouls, but also in reality! Red or pinkish eye color is found only in albinos. This color is associated with the absence of melanin in the iris, so the color is formed based on the blood circulating in the vessels of the iris.

Purple eyes

The most unusual and rare eye color is deep purple. This is extremely rare, perhaps only a few people on earth have a similar eye color, so this phenomenon little has been studied, and there are different versions and myths on this matter that go back centuries.

Eyes of different colors

This phenomenon is called heterochromia, which means “different colors” in Greek. The reason for this feature is the different amount of melanin in the irises of the eye. There is complete heterochromia - when one eye is one color, the other - another, and partial - when parts of the iris of one eye are different colors.

Can eye color change throughout life?

Within one color group, color can change depending on lighting, clothing, makeup, even mood. In general, with age, most people's eyes lighten, losing their original bright color.

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The human eye consists of the eyeball and accessory organs. The apple has a spherical shape and is located in the cavity of the orbit.

The middle shell of the eyeball is rich in blood vessels and itself consists of three parts: the anterior (iris) or iris (in the form of a flat ring with a pupil), the middle (eyelashes), and the posterior (a collection of blood vessels and nerve fibers).

Color human eye determined by the color of the iris. Its hue, in turn, is determined by the amount of melanin in the anterior layer of the iris (the posterior layer has dark pigment; albinos are an exception) and the thickness of the fibers.

It happens that eye color changes throughout life, you can read about this.

Basic colors of the human eye

Melanin affects the color of the iris, hair and skin.

Melanin affects the shade not only of the iris, but also of hair and skin. The more it is contained in the body, the more “eastern” a person looks, that is, melanin colors brown, black, brown.

Brown is the most common eye color in the world. The iris contains a large amount of melanin, the fibers are quite dense.

The prevalence of this shade is explained by its “usefulness”: dark eyes resist both the bright light of the sun (among the southern peoples) and the blinding glare of snow and glaciers (among the peoples of the north).

As a result of evolution and migration, which occurred most actively from the 1st to the 5th centuries AD, this eye color is found on all continents and in all races.

Blue

WITH scientific point vision, blue eyes does not exist. The appearance of this shade of the iris is due to a small amount of melanin and a high density of stromal fibers ( connective tissue). Because it is bluish in color, light reflects off it and makes the eyes appear blue. The higher the density of collagen fibers, the lighter the shade.

The decrease in melanin production in blue-eyed people is due to a genetic mutation that dates back 6-10 millennia. This eye color is most common among Europeans.(about 60% of the population), but also occurs among Asian peoples. Among Jews, the birth rate of blue-eyed children is more than 50%.

Blue eye color indicates a small amount of melanin and a low density of stromal fibers. The lower this density, the richer shade. Mostly infants have such eyes.

Gray eyes are similar to blue ones, but the eyes gray the density of the fibrous body of the stroma is slightly higher. The shade of gray will depend on the degree of light scattering. At increased content melanin, yellow or brown pigment spots are possible.

This eye color is most often found in Europe and countries such as Afghanistan and Pakistan.

Swamp

Swamp eye color – mixed. Depending on the light, it appears brown, hazel, golden or green. The number of melanin cells producing brown, small, the admixture of blue or gray depends on the thickness of the stromal fibers.

As a rule, the iris of swamp eyes is heterogeneous; there is a large number age spots. You can find such eyes among Indians, Europeans and peoples of the Middle East.

The green iris contains a small amount of melanin; The light brown or ocher pigment of such an iris merges with the diffuse blue tint of the stroma and the result is green.

Like swamp green eyes, green eyes do not have an evenly distributed shade.

Pure green is very rare, is more common among residents of all regions of Europe. According to recent studies, mostly women are born with eyes of this color.

According to some reports, the so-called The red hair gene is a recessive gene in the human genotype.

Black eyes are similar in structure to brown ones, but the amount of melanin in the iris of such eyes is very large, ending up on the iris sunlight almost completely absorbed.

Such eyes are common among the peoples of Asia.. Babies in such regions are immediately born with melanin-rich eye membranes. Pure black eye color occurs with albinism (oculocutaneous type).

Rare eye colors

Unusual iris color is usually caused by various disorders: genetic mutations or other failures in normal operation body.

Albinos have red eyes (ocular type of albinism). In the iris of such people there is no melanin, both in its outer layer and in the inner layer (which, as mentioned above, has a dark color). The color of the eyes in this case is determined by the blood vessels.

In very rare cases, the red color may take on a purple tint due to the blue color of the stroma, but this phenomenon practically does not occur. Albinism accounts for only 1.5% of the entire world population. Often accompanied by visual impairment.

Violet

The phenomenon of lilac eyes is practically not studied. It was called the “origin of Alexandria”: according to Ancient Egyptian myth, the inhabitants of a small village saw a strange flash in the sky and considered it a sign from God. That year, the women of the settlement began to give birth to children with unusually beautiful eyes.

One of the first was the girl Alexandria: in the first year of her life, her eyes changed from blue to purple. Subsequently, she had daughters, and each of them had the same eyes. The clearest example person with this pathology is Elizabeth Taylor: Her iris had a lilac tint. People with this eye color are even rarer than albinos.

Lack of iris

The phenomenon in which the iris is completely absent is called aniridia. It can be caused by deep trauma to the eye, but the most common type is congenital aniridia, which is a consequence of a gene mutation.

People with this pathology have jet black eyes. As a rule, the mutation is accompanied by visual impairment: hypoplasia, etc.

Eyes of different colors

One of the most beautiful mutations eyes is considered heterochromia. It is characterized different colors irises of the left and right eyes or unequal color of different parts of one eye, that is, it can be complete and partial.

There are both congenital and acquired heterochromia.

She may develop as a result of serious diseases or injuries of the eye(siderosis, tumors). Partial heterochromia is much more common, even in practically healthy people.

In animals (dogs, cats) this phenomenon is much more widespread than in people (white cats, huskies, etc.).