For many reasons, eyes do sometimes change colors. Trauma can be one, such as a BB hitting you in the eye, or a stick whacking you in the eye can cause your eyes to change colors. Often pregnant women will notice a deepening, or change in their eye color, which is benign and often kind of fun when people notice it. Contacts can also change your eye color, but you already knew that. If your eyes take on a yellow hue, or change color drastically, it may be worthwhile to just speak with your eye doctor to be sure nothing is wrong.