Why UV Protection is important? Fashion aside, sunglasses serve an important purpose: protecting eyes from the harmful rays produced by the sun. You're probably well aware of the need to protect your skin from the sun, but it's equally important to protect your eyes. What to Look for When You're Buying Sunglasses Sunglass standards for lenses place limits solely on UVB and UVA rays, but bear in mind that both the standards and labeling are voluntary, not mandatory. According to these standards, sunglasses must block at least 70% of UVB and at least 60% of UVA. To best protect your eyes, look for sunglasses that provide at least 98% protection from both UVA and UVB rays. UVC rays are blocked automatically since they are absorbed in the atmosphere and do not reach the earth. Some of the higher-priced products with polycarbonate, glass or plastic (CR-39) lenses can claim to block 100% of the UV rays.