The box must be cleansed thoroughly and weekly and changed once three months. Our skin can obtain adequate metablism through enough sleep, however, cornea will be in a continuing state of hypoxia for that it can't absorb the oxygen from the air directly after a nap or overnight sleep wearing contact lenses. Therefore, cornea will get damage in varying degrees after a nap or overnight sleep weraing lenses, at the same time that will lead to the decrease of wet degree on the surface, and eventually result in risk that sunglasses frames lenses cling to cornea.