Well, you are not supposed to wear contact lenses in the water while doing water polo. First, you should know that it can be kind of dangerous for you to do this. As we know that when you have contact lenses in the water, it can be moisten by the water. In that way, there will have many different kinds of virus which can invade your eyes and the contact lenses, and then they can make your eyes infected. In some cases, it can lead to serious eye diseases, such as pink eyes. So anyway, you should not do it. Besides, if you want to say things clearly, I suggest you go to the glasses stores, where they can provide you many glasses which are specially used in water.