Why does eye color change?
Eye color (as well as skin and hair) is largely determined by the amount of melanin in the human body. One of the functions of this pigment is to protect against ultraviolet radiation. In the womb there are no UV rays. Therefore, the content of melanin in newborns is minimal. In the first months of life, its number increases, respectively, the eye color changes in babies (many babies are born blue-eyed, and with age this color changes to a darker one).
If we talk about how much the eye color changes more or less accurately, then we can name the age of about six months. Usually by this time the eyes acquire a color that practically does not change with age.
Another mechanism for changing the color of the iris is not in chemical processes associated with pigments, but in an optical phenomenon. The iris becomes larger with age (of course, this applies only to children). Changing the size of this shell leads to darkening of the eyes.
In adulthood, some people sometimes develop pigment spots on the iris, which differ from the main tone in the darker side. These spots are "analogs" of freckles.
At an advanced age, the production of melanin decreases. As a result, the hair turns gray and dark eyes become lighter. At the same time, the old iris becomes much denser and less transparent. Therefore, the bright eyes of older people darken. That is why eye color changes with age.
Diurnal color changes
Can eye color change during the day? Pigmentation does not change so quickly. However, our perception of colors depends on a number of factors. The main ones are object size and background. Therefore, the color of the iris of the same person in the light of a dim lamp in the dark and in the light of the sun can be perceived differently.
In addition, bright light narrows the pupil of the eye, which leads to the fact that the visible part of the iris increases and appears lighter. In the dark or in poor lighting (as well as under the influence of alcohol or emotional factors), the black pupil becomes much wider, and this leads to visual darkening of the eye against the background of dim lighting.
When blood pressure rises, the blood vessels in the area of the eye overflow with blood, while the whites of the eyes turn red. Sometimes the vessels burst, which leads to temporary bruising (eyes are "poured with blood"). Such a change in the background, on which the iris is located, can lead to a feeling of a change in its tone.
Eye pigmentation does change with age. First of all, this is due to a change in the concentration of melanin. All visible eye color changes during the day (or several days) are an optical illusion.
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