Heterochromia - eyes of different colors. what does this mean and what are the reasons?

Causes of heterochromia

Eye color is determined by the iris. After birth, children in most cases have blue or blue-gray eyes. This is due to very low levels of melanin in newborns. Exposure to sunlight causes changes in eye color. But the final color is determined by the concentration of melanin in the iris. Direct proportionality applies here - the more melanin in the iris, the darker the eyes. But eye color is also influenced by other factors, which is why every person in the world has a unique eye color.

In northern countries, the population is predominantly blue-eyed, while in southern coastal regions, where sunlight is more intense, residents are predominantly brown-eyed. The natural conditions of mid-latitudes do not require a specific color, so our people have almost all colors, while none of them predominates.

Genetics of heterochromia

The genetic basis is determined by the amount and distribution of melanin. Gradually, with increasing research and study of genetics and cellular chemistry, it was found that melanin is influenced by genes for brown and blue on chromosome 15, and for green and gray on chromosome 19.

Newer and more advanced genetic models do not yet work perfectly, as it has been discovered that there is at least one more gene that determines eye color. This is also the gene for the brown type on chromosome 15. In addition, scientists have discovered that a brownish-yellow pigment called lipochrome appears in the iris in green, blue and brown colors.

People with genetically determined heterochromia generally do not have other health problems or negative symptoms. But rarely is this disorder a manifestation of a congenital (present from birth) disease.

Some of these diseases include:

Horner's syndrome
. A rare disorder caused by damage to the nerves connecting the brain and eyes. Usually only one side of the face is affected. The disease is characterized by convulsive eyelids and persistent narrow pupils on the affected side.
Waardenburg syndrome
. A group of genetic disorders that cause changes in eye, hair, and skin color. A more rare manifestation is hearing impairment or loss.
Piebaldism
. This is a relatively harmless condition, which is characterized by a deficiency of pigment in the skin, hair, and eyes. People with this disorder usually have lighter areas of their hair, skin, and eyes than the rest of their body.
Sturge-Weber syndrome
. A disorder in which brain, skin and eye disorders are caused by abnormal development of certain blood vessels. A person with this syndrome has pink, reddish, light purple spots on the face.
Parry-Romberg syndrome
. In this disorder, the skin, soft tissue, muscles, and sometimes bones on one side of the face slowly weaken and atrophy over time. This is a very rare disease. A sick person suffers from frequent seizures.
Hirschsprung's disease
. A disorder that affects the large intestine. The condition predominantly occurs in newborns and infants and is characterized by impaired bowel movements.
Tuberous sclerosis
(Bournville syndrome). A rare disease characterized by the formation of benign neoplasms in various organs of the body (most often the skin, brain, heart, lungs, kidneys, eyes are affected).
Duane's syndrome
(Duane's retraction syndrome). The disorder is characterized by an impairment in the ability of one or both eyes to move inward and/or outward.

Sometimes the cause of heterochromia is a health condition. Many people have noticed that during illness or severe stress, their eyes become darker or lighter. This phenomenon is related to the distribution and density of melanin or lipofuscin in the iris. But the exact mechanism of this temporary disruption is not yet fully understood.

Another cause of heterochromia is the use of certain medications. The mechanism of action of drugs on changes in eye color is only partially explained, but it is believed that the drugs have an effect similar to the effect of the hormone prostaglandin secreted in the human body.

A certain effect of hormones on the pigmentation of the iris has been partially proven. This also explains the change in eye color in the adult population.

The next cause of heterochromia taken into account is a mole growing on the iris. It can cover a third, half, even the entire area of the iris. Consequently, an initially blue eye may gradually “transform” into dark brown.

When a mole appears, it is advisable to pay close attention to this condition. Ophthalmologists warn that it can develop into melanoma, which requires removal of part of the iris.

Classification and causes

Partial heterochromia: blue iris with a brown sector

Complete heterochromia

Heterochromia is classified primarily as genetic or acquired. Although a distinction is often made between heterochromia of the eye: complete

(Greek heterochromia iridis) and
partial
.
With complete heterochromia,
the color of one iris is different from the color of the other.
With partial heterochromia
or
sector heterochromia,
the color of one part of the iris is different from the color of the remaining part.

Congenital heterochromia

As a rule, it is inherited as an autosomal dominant trait.

Abnormal darkening of the iris

Lisch nodes are one of the symptoms of neurofibromatosis
Uveal melanoma
Pigment dispersion syndrome - characterized by loss of pigmentation on the posterior surface of the iris, which spreads intraocularly, and is applied to various intraocular structures, including the anterior surface of the iris
Sturge-Weber disease

Abnormal lightening of the iris

Simple heterochromia is a phenomenon characterized by the absence of other ocular or systemic problems. Abnormally light eyes are usually considered to be iris hypoplasia. It can manifest itself either completely or partially.
Waardenburg syndrome
Horner's syndrome
Piebaldism is the presence on the skin of the limbs, face and some other parts of the body of congenital white spots, completely devoid of melanocytes; is inherited in an autosomal dominant manner and is caused by various mutations.
Hirschsprung's disease
Bloch-Sulzberger syndrome
Parry-Romberg disease (Romberg syndrome)

Abnormal darkening of the iris

Corneal iron deposits - siderosis
(deposition of iron in the tissues of the eye) and hemosiderosis.
Certain eye drops that are used externally to reduce intraocular pressure in patients with glaucoma. Occurs due to stimulation of melanin synthesis in the iris
Tumor
Iridocorneal endothelial syndrome

Abnormal lightening of the iris

Fuchs' heterochromic iridocyclitis - as a result of intraocular inflammation, atrophy of the iris occurs and heterochromia characteristic of this condition occurs.
Horner's syndrome is usually acquired due to neuroblastoma, but can also be congenital.
Melanoma can also cause lightening of the iris.

In addition, heterochromia can be caused by Stilling-Turk-Duane syndrome, mosaicism, uveitis, juvenile xanthogranuloma, leukemia and lymphoma.

Types of heterochromia

Heterochromia is a disorder characterized by the presence of 2 or more different colors of the iris. There are several different variations of this disorder.

First of all, it is classified by the difference in iris color:

hypochromic heterochromia - an “abnormal” iris that is lighter than normal;
hyperchromic heterochromia - an “abnormal” iris that is darker than normal.

Partial (sector) heterochromia

Partial heterochromia is characterized by a partial change in the color of one eye. For example, a person may have half of the iris of one eye color, and the other half a different color. At the same time, the other eye is monochromatic. Also with this type there are spots of different sizes on the iris or a different shade in the center of the pupil.

This disorder is quite rare, occurring in 1 person out of 2-4 million. In children, the appearance of this phenomenon is due to a lack of pigment in the body during the formation and final color of the iris, which is why it is only partially colored.

Complete heterochromia

With complete heterochromia, the color of the eyes (iris) is completely different. For example, a person has one iris that is blue and the other is brown. This combination of different shades looks very impressive, unusual, and attractive. As a rule, no function of the visual organs is impaired.

Central heterochromia

Central ocular heterochromia is the most common occurrence and is characterized by the presence of several colored circles in the central part of the pupil. In most cases, a person does not even suspect that this disorder relates to heterochromia. This feature is not dangerous and does not cause visual discomfort.

Metallosous heterochromia

Metallic heterochromia is characterized by a change in the shade of the pupil due to mechanical damage by a foreign body (copper or iron). Depending on the type of metal, the damage is divided into siderosis or chalicosis. Along with manifestations of the inflammatory process in the eyeball, the color of the pupil changes. Most often it becomes dark brown, less often green or blue.

Changes in iris color

When the eyes are of different colors, the following pathological changes in the iris can be identified:

Posterior synechiae may be present. As a rule, they can be after treatment and removal of cataracts;
Atrophy of the tunicate stroma of the iris, in which there are no crypts and color saturation decreases;
Pigment spots may appear on the back layer. They are clearly visible under retroillumination;
Nodules appear on the iris;
Rubeosis of the iris (neovascularization) of irregular shape is formed;
The appearance of mydriasis (dilation of the pupil) due to atrophy of the pupillary sphincter;
Deposits in the form of crystals may be observed in the iris;

How to get heterochromia

Many people dream of changing their image by changing their eye color, but how to purposefully get heterochromia and give your eyes different shades?
This can be done in several ways. Safe methods:

Cloth
. This option is suitable for those with light pupils. For example, the color gray becomes blue when wearing blue-colored clothing.
Cosmetics
. Everything is simple here. Use shadows of the color you want to give the pupil.
Color contact lenses
. You can use either one or both lenses.

Dangerous methods:

The use of antiglaucoma drops
. When using the product in accordance with the instructions, a change in the shade of the iris will occur within a few days. The phenomenon is reversible, but not completely safe. Drops lower intraocular pressure, which can cause visual impairment in a healthy person.
Application of laser
. The method has not been sufficiently tested by research, so it cannot be considered safe.

There are also a number of diseases that contribute to the appearance of different-colored eyes (acquired heterochromia) at any age, including the following disorders:

Neuroblastoma
. A type of cancer in which a tumor begins to develop in the nerve cells of the sympathetic nervous system. The disease primarily affects infants and preschoolers.
Fuchs syndrome
(heterochromic cyclitide syndrome). It is a disorder that most commonly affects adults and older adults. The disease is characterized by blurred vision (fog before the eyes), pain in the eyes, and photosensitivity. The disease is caused by damage to corneal cells, whose main function is to regulate the amount of fluid in the cornea.
Glaucoma
. This is a progressive disease, most often caused by increased intraocular pressure. This condition causes fluid to rise in the front of the eye with subsequent damage to the optic nerve.
Central retinal occlusion
. A vascular disease that causes blood and other fluids to leak into the retina.
Melanoma of the eye
. This is an oncological disease in which a tumor develops in the eye cells that produce melanin.
Trauma
, eye injury.
Ophthalmic operations
.
Some drugs
used in the treatment of glaucoma.
Diabetes
.

With a genetically determined disorder, there are no risk factors associated with heterochromia. Moreover, it is not a disease as such. But the disorder caused by the disease requires attention - it can cause serious consequences.

Since changes in the color of the iris can cause diseases (including serious ones), if this disorder occurs, it is advisable to consult a doctor.

Interesting fact:

If one identical twin has heterochromia, the other will also have it. What is the reason for this? Heterochromia occurs in 2% of the world's population, which is not very high. The main reason for this difference is the amount of melanin in the human body.

As mentioned above, most children, especially white children, are born with neutral eye color. When the eyes are exposed to sunlight, the melanocytes in the iris begin to produce melanin pigment, causing the eye color to gradually change towards the color of the parents' eyes. Melanin density in the 1st year of life is about 50% of the melanin density of an adult. Pigmentation is completed in the 3rd year of life.

Changes in eye color in adults are also interesting. As is known, it is the result of the reflection of light rays from the environment from the structure of the iris. People with brightly colored irises often claim that their eye color varies depending on the color of their clothing. This is not surprising, because in this case the color of the iris is also caused by a combination of colors reflected from clothing or even makeup, and not always in the way one would expect.

How to intentionally get a disease

There are several ways to change your eye color

Some of them are completely safe and can be used frequently, while others should be treated with caution. Safe methods include:

Selection of clothes of a certain color. If you want to change the shade of your iris, just choose clothes of a certain color. Thus, gray eyes will acquire a blue tint if there are some details of a rich blue color in the clothes.
Lighting will also help change your appearance. In bright light, the eyes become brighter and more attractive. In a poorly lit room, the iris darkens somewhat.
It is easy for representatives of the fair sex to change the shade with the help of decorative cosmetics. You just need to apply a little eyeshadow on your eyelids in the color of your eyes.

You can very quickly change the color of your eyes using contact lenses. In this case, you can change the shade of either one organ of vision or two at once. Lenses should be purchased at specialized optical stores or ophthalmology offices.

It is important to wear and store lenses correctly; it is worth considering that they also have an expiration date

You should not use contact lenses if you have infectious eye diseases.

There are several ways to change eye color, which doctors consider potentially hazardous to health:

Drops are put into the eyes to treat glaucoma. In just a few days, the iris begins to change color. This condition is reversible.
You can use drops based on the hormone prostaglandin. Such drugs help lower eye pressure, but they also impair the nutrition of the tissues of the visual organs.

In America, a technique for changing color using a laser was developed. But to date it has not yet been sufficiently tested. Therefore, it is premature to talk about its effectiveness.

Heterochromia is not a disease, but just a feature of the body. If you want to specifically change the shade of your iris, it is best to use colored lenses. This is the safest way to achieve the effect of heterochromia.

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Treatment of heterochromia

Treatment of heterochromia begins with determining whether the deviation is harmless, just an aesthetic disturbance, or represents a symptom of a disease that requires treatment.

The diagnosis is made by an ophthalmologist; in the case of other diseases, a consultation of several specialists is required. During the diagnosis, the fundus of the eye and the condition of the optic nerve are examined, and possible visual impairments are excluded. Visual acuity, etc. is also assessed.

The disease is suspected if heterochromia develops over time rather than being present from birth.

In most cases, we are talking only about the aesthetic side of the issue. In this case, no treatment is required. If this disorder bothers a person, colored lenses can be used.

A completely different approach is required if heterochromia of the eyes is caused by an ophthalmological disease or a disease affecting other organs. In this case, we are talking about one of a number of symptoms. Therefore, it is necessary to eliminate the root cause of the violation. Depending on the pathology, the advisability of drug treatment or surgical intervention is considered.

According to the primary disease, one or more of the following therapeutic approaches is selected:

drug therapy;
laser correction;
steroid treatment;
vitrectomy.

Drug therapy

The first step in case of chalicosis or siderosis is the removal of the foreign body that caused the disorder. For inflammation, corticosteroids, antifungal or antibacterial drugs, and anti-inflammatory drugs are prescribed. Local therapy using steroid drugs is sometimes used.

Laser correction

The procedure involves removing excess pigment with a laser beam. It only takes a few minutes, but positive changes are only possible if the dark tint is eliminated. Full color restoration occurs within 3-4 weeks after the procedure.

Surgical intervention

Some ophthalmological diseases (in particular, diseases of the lens) require a surgical approach - vitrectomy. The surgical treatment method involves installing an implant. But it has not been sufficiently researched, and it is not allowed in all countries.

Heterochromia in cats and dogs

Heterochromia is common in some animals. It is most common in cats and dogs, such as the Japanese Bobtail, Turkish Angora, Siberian Husky, Australian Shepherd, etc. A “regular” white European cat can also have unevenly colored eyes. Heterochromia also occurs in horses and cattle.

Uneven coloration in animals, as in humans, is most often caused by an uneven distribution of pigment, melanin. This occurs, for example, due to a genetic disorder, Waardenburg syndrome, and often does not pose any danger to the animal.

Etiology and pathogenesis

Of course, there is no reason to be afraid of heterochromia, especially since it does not affect human health in any way. Moreover, a person with heterochromia continues to see and perceive colors absolutely normally, as if he did not have heterochromia at all!

By its nature, heterochromia is nothing more than a unique phenomenon, manifested by cell mutation immediately after fertilization. Meanwhile, abnormal eye color can become acquired as a result of an eye injury or as a complication after an illness.

Most often, heterochromia occurs in women, less often in representatives of the stronger half of humanity. With heterochromia, the stroma of the “iris” is depleted of pigment, which occurs due to trophic (congenital) disorders generated by organic or functional transformations in the sympathetic nervous system.

Heterochromia in celebrities

Heterochromia of the eyes makes a person easily memorable and eye-catching. Do you also think that David Bowie is unique among celebrities because of his eye color? The multi-colored iris effect among famous faces is more common than it seems.

In addition to David Bowie, some other stars have heterochromia in their eyes. For example, Jane Seymour (Doctor Quinn), her younger colleague Kate Bosworth (Big Sur), Alice Eve (Men in Black 3) can boast different shades of pupils. Josh Henderson from the sequel to the series "Dallas" has one eye bright green and the other blue.

The charming Mila Kunis from “Black Swan”, the English handsome man and modern Superman Henry Cavill, the main character of the film “24” Kiefer Sutherland have a less expressive difference in the color of the iris.

Other celebrities with heterochromia: