The eye color of a newborn baby can change dramatically in just two years.
The protective pigment in the rainbow shell of the eye
In 2016, a study by Stanford School of Medicine found that out of 148 children, one third had changed the colour of their eyes in the first two years, but only five children had light eyes.
In 1997, another American study followed more than 1,300 twins from childhood to adulthood, and observed that the colour of these children's eyes usually ceased to change from the age of six; however, in some exceptional cases, these changes continued to occur in adolescence and adults, and scientists also observed that heterosogotic twins have originally similar colours.
Unknown environmental factors
The color of the eyes depends, inter alia, on the amount of melanine, the pigment, which also determines the color of the skin. But melanine also plays an important role in protecting against the sun. This explains why dark eyes are more resistant to sunlight than light. In the eyes of a small number of melanine, blue is the result of the collagen fibers spreading light. This is like what happens in the sky.
However, there are no studies that explain why many children develop more melanine as they grow up, so their eyes turn dark. Scientists admit that they do not really know what causes these colour changes, although there is some belief that there is interaction between genetics and the environment. However, the environmental factors causing such effects are still unknown.
Finally, although eye color changes are not usually serious, sometimes they can be connected to something serious, for example, an injury can change the color of the eye.