Szemszín

Szemszín refers to the color of the iris of the eye. This coloration is determined by the amount and type of melanin pigment present in the iris's front layers. The most common eye colors globally are brown, followed by blue and hazel. Green and gray eyes are less common, and other colors like violet or red are extremely rare and usually associated with specific genetic conditions.

The genetics of eye color are complex, involving multiple genes. However, the OCA2 gene is a primary determinant, influencing the production of the P protein, which is involved in melanin production and transport. Another significant gene is HERC2, which regulates OCA2 expression. Brown eyes have a high concentration of melanin, absorbing most light wavelengths. Blue eyes have very little melanin; the blue color is an optical effect caused by the scattering of light in the stroma of the iris, similar to why the sky appears blue (Rayleigh scattering). Hazel eyes exhibit a mix of melanin concentration and scattering effects, often appearing brown near the pupil and green or blue towards the periphery.

Eye color can change over a person's lifetime, particularly in infants. Many babies are born with blue or gray eyes, which may darken as melanin develops in the iris during the first few months or years of life. In rare cases, eye color can change due to injury, disease, or certain medications, but this is not a typical developmental process.