According to statistics, about 1% of the total population of the globe has eyes of different color. This phenomenon is called “heterochromia” and invoked by a number of reasons, congenital or acquired.
The eye color is determined by the presence of the pigment melanin in the iris, produced by the cells of melanocyte. The concentration of the coloring pigment affects the color of the iris.
In most cases it is the same for both eyes and presents the basic colors (blue, yellow, brown) and their variations. But sometimes due to some internal or external factor the eyes turn out different.
Heterochromia is inherent not only to man. It occurs also in animals, such as cats and dogs.
- The eye colors are completely different (for example, one iris is blue and the other is brown).
- In this type of heterochromia, two shades are present in one iris. One of them is dominant and the other presented in the form of diffuse spots or is a separate sector of the iris.
- In this case, different colors combined in one eye so that the dominant tone is a big part of the iris and the other color ring colors the center of the eye, creating a halo around the pupil.
Congenital Causes of Heterochromia
In most cases, heterochromia is hereditary. Due to this fact, a child is born with eyes of different color because of mutations in the chromosomes.
This anomaly does not affect the sharpness of the vision and does not create any problems but aesthetic. In today’s world, people with eyes of different color, if desired, can use tint contact lenses.
Sometimes genetic abnormalities lead to more serious disorders in which differently colored eyes are just one of the pathological symptoms.
Such diseases include:
- Degeneration of the cervical sympathetic nerve;
- A pigment dispersion syndrome;
- Waardenburg syndrome;
- Fuchs’ syndrome;
- Sturge—Weber disease;
- Uveal melanoma;
- Horner’s syndrome;
- Hirschsprung’s disease.
Eyes of different colors: acquired causes
- Mechanical injuries of the eyeball;
- Inflammatory disease of the body;
- Malignant neoplasms;
- Iron deposition in ocular tissues;
- Side effect of some eye medications.