As we know, the color of eyes is determined by genetic genes which will not change easily. It is related with iris. When you find that your eye color changes, your body may have the problems. However a lot of people could change the eye color easily to make them look beautiful. They wear the contact lenses. That is the main reason. The colored contact lenses could make them look beautiful and big at the eyes.
All right, you are very interested in the question aren't you? Anyway, typically speaking, our eye color would not change throughout my lifespan, but sometimes, diseases would let it happen, let's take glaucoma and cataract for examples, they would turn your eyes green and white respectively, leading to a lot of problems and great damages to your eyes. Thus, it could be seen as a health warning. Just be careful.
Eye color is decided by gene, that is, when you were born, your eye color has already come into being. But with time flies eye color will change gradually with living environment and habits and customs, such as eating habits, smoking and liver diseases. Also, aging is also one factor that leads to eye color changing. Eye color will become lighter and lighter when we are in 50s-60s.