Skip to main content

Different Color Eyes: Heterochromia Explained

You must at one point met someone with a different eye colors as compared to the normal colors that you are used to. In most cases, you will find that these individuals are wearing contact lenses, whereas in other cases, this is the real eye color of an individual. David Bowie, Kate Bosworth, Christopher Walken and Dan Aykroyd all have different eye colors. Most people mistake their eye color to wearing contact lenses. In less developed places, people with different eye colors form the rest are considered to be having underlying eye conditions that need correction. However, this is not the case as there are some people who are born with naturally different eye colors.

It is often very difficult to tell the exact eye color of another person, unless you get a closer look at their eyes. Green eyes may look blue and black may look brown. Getting closer to the person will tell you his or her exact eye color. To understand heterochromia well, you first need to understand what constitutes to eye color. Eye color is just the result of how much pigment one has in the front part of their iris, which is the front part of their eye. Blue eyes come about as a result of zero or slight pigment in the eye, green eyes are as a result of moderate pigment whereas brown eyes are as a result of too much pigment in the eye.

Consequently, the amount of pigment that is found in a person’s eye entirely depends on the genes that are contained in the special cells, known as melanocytes. As a result, people with heterochromia have this condition because it is likely that melanocyte has found its way into one of their eyes. This is what is causing their eye to change color in one eye, and in situations where the melanocyte does not get into the other eye, that particular eye will be blue in color because it lacks the pigment. Melanocyte is known to get into a child’s eye during the infant development stage and gives the eye color. There is no particular determining factor why this happens, and in case the child faces an injury during the development of the new eye color, the melanocytes can die off.

Another genetic disorder that can affect the pigmentation of one’s eye is the Waardenburg syndrome. This genetic disorder affects both humans and animals. In addition to that, there are two other ways through which one can get different eye color. They are known as Mosaicim and chimerism. These two terms are used to refer to humans or animals that have more than one cells that are genetically distinctive. In mosaic, a genetically different type of cell arises from a single zygote, or a fertilized egg, whereas in chimeras, they originate from more than one zygote. Just like nay two siblings can have different eye color, a chimera can also have two different eye colors. This is because each of the cells has a different eye color genes. A mosaic on the other hand, can have two different colored eyes if the DNA is in the eye color gene.

Types of eye heterochromia

There are three main types of heterochromia which include the following;

  1. Central heterochromia

This type of heterochromia is defined by having two different colors in the same iris. Usually, the outer ring of the iris is white, and the inner is another color. The inner ring seems to have spikes of different colors that come from the pupil or the black circle in the eye.

  1. Complete heterochromia

People with this condition have two different eye colors. For instance, they may have one blue eye and one brown eye.

  1. Sectoral heterochromia

In this case, one part of the iris has a different color from the rest of the eye. This condition usually looks like the eye has an irregular spot. No ring is formed around the pupil.

However, most of the causes of heterochromia occur as early as from birth and this is known as genetic heterochromia. Research has also confirmed that most of the cases of heterochromia in human beings occur without any underlying abnormality. This condition just appears naturally in a person. Nonetheless, some of the causes of genetic heterochromia are linked to some diseases and syndromes such as;

  • Bourneville disease.
  • Bloch-Sulzberger syndrome.
  • Horner’s syndrome.
  • Sturge-Weber syndrome.
  • Parry-Romberg syndrome.

Consequently, heterochromia that develops later after birth can be as a result of illness, injury or a particular medication that one is using. This type of heterochromia is known as acquired heterochromia. However, this is a less common heterochromia than the genetic heterochromia. Some of the causes of acquired heterochromia are;

  • Eye surgery.
  • Diabetes.
  • Glaucoma.
  • Pigment dispersion syndrome
  • Injury to the eye.
  • Iris ectropion syndrome.
  • Swelling of the eye.
  • Tumor in the iris.

Furthermore, a medication known as latanoprost which is used mainly in the treatment of glaucoma, has been reported to cause changes in eye color in some patients who are taking it for five years or longer. For instance, David Bowie has different eye color, and his came about as a result of an injury that he had and caused one of his pupils to be permanently dilated. Another condition that can affect the hue in one’s eyes is viral infections, or serious diseases. However, this only affects some people and not everyone.

Some people have questions of whether heterochromia can be treated or not. The answer to that question is that, if there are no issues that are present in the eye, treatment is not necessary. However, if you have underlying eye condition or got your change in eye color as a result of an injury or medication that you should consider looking for the available treatment options. Also, some people may feel very uncomfortable with their specific eye color. People who do not have underlying eye conditions resort to wearing contact lenses to have one eye color. In this case, contact lenses have been used for cosmetic reasons.