Barbara Marquand is a staff writer at NerdWallet, a personal finance website. Email: bmarquand@nerdwallet.com. Twitter: @barbaramarquand.
The eye may change color due to alteration of genes in the cells of the iris. This is because of your DNA factors in the body. The gene alteration can cause the eye to change color from brown to green and vise verse. There is no any explanation to the cause of the genes behaving in these manner. Prolonged exposure to the sun might also be another cause that made my eyes to change the color.
Eye color is determined by the differences in amounts and types of pigments present in the iris. Pigments are determined often by genetic alleles, however some conditions can â¦cause a change in eye color. I would have stopped here however you asked WHY do eyes have color, and not HOW do eyes have color. Hence you may suggest that eye color has some functionality, and you wish to query this. There is no solid link, however empirical studies have some correlations between lighter eye colors and earlier loss of vision (ARMD).