Water or any other non-abrasive sunglass (or regular glasses) cleaning solution will do the trick. However, you want to make sure to use a microfiber or 100% cotton cloth to wipe it down.
The polarized anti-reflective coating (usually on the inside of the sunglasses) CAN get scratched, so make sure to be gentle with it. I always put my sunglasses in their cases when I take them off, especially if they're of high value.
Welcome to Sunglass Forums!