Can dark lenses prevent UV lights?

[eyeglass frames]

I own a pair of sunglasses which lenses are very dark. So when I go out wearing with them, I do not feel the strong sunlight. Do I still need those "UV Protective" sunglasses?

[bifocal glasses]

Absolutely yes! Most people believe that the darkness of the lens can protect their eyes from the UV rays. However, the degree of darkness has no effect on UV rays. For adequate protection, you need to wear sunglasses that indicate they can block 100 percent of the sun's UV rays.