Different eye color in a person: what is called, causes

A rare condition in which eyes are different colors is heterochromia. It can be congenital or acquired, and occurs in humans and animals. Let's look at the features of this anomaly.

The main types of hereditary heterochromia by the degree of iris coloration: [ 1 ]

• Full - one of the most common types, each eye has its own color.
• Sectoral - the iris of one eye consists of several shades.
• Central - the iris has several colored rings.

Types of acquired anomaly due to damage to the iris: [ 2 ]

• Simple - staining due to weakness of the cervical sympathetic nerve.
• Complicated – caused by chronic diseases in which one eye completely changes its color.
• Metallosis - occurs due to metal fragments getting into the eyes, which provoke the development of siderosis or chalcosis.

Most often, women encounter this anomaly. It does not affect visual acuity and does not cause painful symptoms, so it is absolutely safe.

What are eyes of different colors called?

An abnormal condition in which the eyes are different colors is called heterochromia. It occurs due to the merging of pigments in the stroma of the iris. This occurs due to genetic disorders or external factors.

People with this deviation perceive colors in the same way as healthy people. If the phenomenon is hereditary, then medical correction is not required.

Changes caused by trauma and other pathological factors may result in impaired visual acuity and ophthalmological diseases. This condition requires complex diagnostics and treatment.

Why are eyes different colors?

Eyes of different colors arise from a deficiency or excess of the pigment melanin in the iris or part of it. The pigment content in the iris stroma and anterior boundary layer determines all shades of iris color from green to dark brown. An increase in pigment in the iris stroma leads to greater absorption of light and, as a result, to a darker eye color. [ 3 ]

Melanin is an inert biopolymer that exists in two different forms: brown-black eumelanin and red-yellow pheomelanin. Melanocytes have the ability to produce both forms of melanin; however, the ratio of the two forms can vary widely among individuals, producing different shades of hair and skin color.[ 4 ]

In the first decade of the 20th century, two reports appeared in the literature that supported the idea that eye color was inherited as a simple Mendelian trait.[ 5 ] Brown eye color was inherited as a dominant trait and blue eye color was inherited as a recessive trait, with the result that two blue-eyed parents were unable to produce offspring with brown eyes. Although this doctrine was widely accepted, it soon became apparent that blue-eyed parents could occasionally produce offspring with brown eyes, and that eye color was not inherited as a simple Mendelian trait. Indeed, recent research suggests that eye color is inherited as a polygenic trait that is still not fully understood.

A number of genes are involved in determining eye colour: these include OCA2, TYRP1, MAPT and MYO5A. Of these, the genes OCA2 and EYCL3, which are found on the long arm of chromosome 15 (15q11.2–15q-12) and encode brown/blue eye colour (BEY) and EYCL1, which is found on chromosome 19 and encodes green/blue eye colour (GEY), appear to be the most influential.[ 6 ]

After birth, the color of the iris may change, and in Caucasians, the iris at birth is blue due to a lack of stromal melanocytes, which apparently have not yet migrated from the neural crest or differentiated from stem progenitor cells. In blacks, the iris appears gray at birth. The iris usually assumes its true color by 3 to 5 months of age.

There are also causal factors that can trigger the development of heterochromia at any age: [ 7 ]

• Inflammation of the vascular membrane of the eye in Fuchs syndrome causes changes in one or both eyes, blurred vision, and in particularly severe cases, complete loss of vision.
• Side effects of medications used to treat glaucoma.
• Iridocorneal endothelial syndrome.
• Malignant neoplasms of the iris, neurofibromatosis. [ 8 ]
• Hemorrhages in the eyeball, sclera.
• Eye injuries – metal shavings, graphite and other foreign objects entering the visual organs lead to a change in the color of the injured eye.
• Waardenburg syndrome is an uneven distribution of melanin in the upper layer of the iris. [ 9 ]

There are also a number of systemic diseases that lead to changes: mosaicism, chimerism, Wilson-Konovalov disease, leukemia or lymphoma, Stilling-Turk-Duane syndrome and other pathologies.

Famous People With Different Eye Colors

Different colors of the left and right eyes or non-uniform color distribution in one visual organ is heterochromia. This phenomenon is associated with a violation of the normal level of melanin in the iris. About 2% of the Earth lives with the anomaly, including famous people:

• David Bowie, a famous rock musician, suffered an eye injury in his youth. The injured organ completely lost the ability to perceive color and acquired a brown tint.
• Alice Eve is a British actress with complete heterochromia. Her right eye is green and her left eye is blue.
• Milla Jovich is an American actress, model and fashion designer. One of the girl's eyes is blue and the other is green. During filming, she chooses one color and corrects the other with a colored lens.
• Sarah McDaniel is an American Playboy model and popular blogger. She has one blue eye and one brown eye. It is this feature that has attracted worldwide attention to her.
• Josh Henderson is an American actor and singer. He has unique iris colors - sky blue and bright green.
• Jane Seymour is a British actress and is one of the sexiest 007 girls. She has one brown eye and one green eye.
• Kate Bosworth is an American model and actress. She has a sector anomaly - one eye is blue and the other has a brown tint.
• Henry Cavill is a popular British actor with sectoral heterochromia. He has blue eyes with a brown sector in the upper part of the left organ.
• Mila Kunis is an American actress, one of the sexiest women on the planet. One of her eyes is green and the other is light brown.
• Demi Moore is an American actress, her left eye is green and her right eye is brown.

In addition to real celebrities, there are also literary heroes with eyes of different colors: Lieutenant Myshlaevsky from "The White Guard" and Woland from "The Master and Margarita" by Mikhail Bulgakov. The main character of the work "Four Tankmen and a Dog" by Janusz Przymanowski, as well as Tyrion Lannister from "Game of Thrones" by George Martin.