If they wear the contact lenses in the water while doing water polo, they may wear the outer eyeglasses for the eye vision. However, it is not good to wear the contact lenses when playing the water polo because the water contains a lot of bacterium which may easily let your eyes get infection.
Personally, i don't think it will be feel good by wearing contact lenses when play water polo. It may get eyes infection. However, there are some people think it is worth to wear contact lenses while play water polo. By wearing contact lenses, they can help them see better so as to play better in the games. So, maybe you can have a try. Anyway, you can ask your doctor before you do it.
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.