First, the optical correction - cheap rb3025 sunglasses almost no function in this regard, but for contact lens wearers, wearing sunglasses contact lenses can be prevented or reduced water evaporation, keeping contact lenses optical performance.
Second, the protection function - mainly to prevent burns eyes were intense sunlight, but mainly block UV light, UV rays protect your eyes is not, the premise is this pair of sunglasses with UV blocking lenses must function.
Third, decorative purposes - many people choose sunglasses styles and colors start to consider, because many people sunglasses in the summer to become the ideal decorations. Even when the sun is not very strong season or indoors, there are young women will be wearing sunglasses on his head, or hang in closets for decorative purposes.
Four, blocking sunlight - cyclists, drivers, outdoor workers, fishing enthusiasts, outdoor sports, water sports persons, ice movement, etc., by wearing sunglasses to block the sun, enhance visual clarity.