Sunglasses which are labelled as "UV 400" or "100% UV protection" have the best UV protection. This kind of sunglasses lenses can block all the UV rays, including UVA and UVB rays. Sunglasses lenses made of polycarbonate have 100% UV protection itself in the lens material. If they are not made of polycarbonate, they should have 100% UV protection coating on the lenses. What's more, polarized sunglasses are the best one for outdoor activities. They can not only have UV protection but also block the glare which may affect the vision.
As we know, sunglasses are worn for shield eyes from strong light and UV rays. So, a pair of qualified sunglasses shall have the UV protections. So, you needn't look for especially sunglasses lenses for UV protections. If you want to get better eye protection, you can choose sunglasses with polarized lenses which can not just blocking UV rays, but also prevent glares from water surfaces or some metal pieces so as to give your Better eye care.