Interesting facts about eye colour | How does eye colour come about?

Interesting facts about eye colour

  • About 90% of the world population has brown eyes. – Especially among Europeans, most newborns are born with blue eyes. The formation of melanin by the melanocytes does not begin until the first weeks of life, so that the final eye colour only shows after a few months to years.
  • In albinism the pigment epithelium of the iris is completely missing. Thus the eyes appear very light blue to almost pink. – Rarely are the two eyes of a person of completely different colour.

This is then called iris heterochromia (heteros – unequal and chroma – colour). If one eye alone is of a different colour, this is called partial heterochromia. Heterochromia can be congenital or acquired, for example, through trauma.

What are the frequencies of eye colour?

The variety of eye colour varies between the different colour gradations from brown to blue. The colour of the iris (iris skin) is inherited on several genes and is an interplay of many factors. Brown is the most common eye colour in the world population with about 55%.

One of the reasons for this is that the trait is dominant (prominent) in heredity compared to the other eye colours. Especially in Asia, Australia and Africa, the basic colour of the iris is brown in the majority of people. Green-brown eyes have about 5% of people.

If there is hardly any melanin in a person’s genetic make-up, this leads to blue eyes. 8% of the world population have blue eyes. Estonia is the country with the largest proportion of blue-eyed people, 99% of the population there.

Blue as a genetic trait is recessive to brown, i.e. receding. Researchers therefore suspect that blue eyes will become less common in the future. The occurrence of people with brown eyes, however, will increase. Green eyes account for only 2% of the world’s population, although green is more common than blue in heredity. – Brown colour

  • Green-brown colour
  • Blue color
  • Green colour

Is it possible to change the colour of the eyes with the laser?

With a certain form of laser, keratopigmentation, it is now possible to change the colour of the eyes. In this procedure, colour pigments are inserted under the cornea with a laser. This is done under local anesthesia in 1-2 procedures, each of which takes about 30 minutes.

The reasons for the procedure can be very different: It is significant that neither a foreign body is introduced into the eye nor the inner structure of the eye is changed. In some cases, keratopigmentation can prevent the need for an ocular prosthesis. Alternatively, there is also the method of iris implantation for a permanent change in eye colour.

In this method, a stained lens is inserted into the posterior chamber of the eye. Both methods, the laser eye colour change and the iris implantation, have certain risks, like all surgical procedures. Therefore, they should only be performed in specialized centers and after careful consideration.

  • Therapeutic for corneal opacity
  • Functional in anatomical pathologies
  • Purely cosmetic

Already in ancient times people tried to change the colour of eyes by tattooing. Especially in cases of stigmatization by diseases of the eye. A relatively new method is keratography, in which colour pigments are inserted into the cornea with a needle.

This is done under local anaesthetic. Medical reasons for the intervention are, for example, albinism, absence or tearing of the iris, coloboma or keratoconus. Keratography can also be performed for cosmetic therapy in cases of corneal opacity or after accidents with damage to the eye.

In most cases, tattooing the cornea is an uncomplicated and quick procedure from which patients recover quickly. In principle, however, the procedure is only recommended for patients who have already lost their sight before, as the risks are relatively high. In the worst case, complications can lead to blindness.