The true determinant of a sunglasses' UV protection ability is the UV protection technology of the lens itself, not the darkness of its tint. High-quality PC sunglasses typically use UV400 protection, effectively blocking ultraviolet rays with wavelengths below 400nm and filtering over 99% of UVA and UVB rays.
PC material itself has a certain UV absorption capacity, and combined with professional UV protection technology, it can effectively reduce the damage caused by ultraviolet rays to the cornea, lens, and retina.
