The most important benefit of wearing sunglasses is that they protect your eyes from ultraviolet (UV) light. UV light can have harmful effects on the eyelid, cornea, lens and retina. They protect not only your eyelids but also the retina and cornea of your eye. Wearing sunglasses all year is a good idea because UV light can cause damage even on cloudy or snowy days. Sunglasses also prevent those UV rays from causing skin cancer around your eyelids.