If you die naturally, your eye's color will not change. If you die because of some diseases, your eye's color may be changed. If there is something wrong with your liver, your eyes may become yellow when you die. The color of the eyes will not change if you are in the healthy state. Thus you could observe the health of the eyes from the color of the eyes.
Well, from what I know, the color of your eyes would simply not change unless you have got some trauma on your eyes. However, when you finally die, your eyes would be dilated and that is a natural stuff. So, I suggest that you should try to take care of your eyes, and if you want to change the color of your eyes , you might as well wear a pair of circled contact lenses, and try not to do anything stupid.