You just need a pencil eraser to rub the sunglasses until the scuff marks disappeared. Then, spray some water on the scuff. Keep it for about 1 minute, and you can remove the scuff as much as you can by rubbing the water into the scuff mark. At last, use the glass cleaner to do the same as the second step.You should take care of you glasses at other times. Firstly, use both hands when you wear or take off your glasses. Secondly, keep the mirror up when placing the glasses. Thirdly, use special glasses cloth to wipe away your glasses. What's more, try to avoid making glasses contact with moisture, lampblack, sweat and some cosmetics, etc. At last, don't keep them in high or low temperature environment for a long time.