The meaning of the UV400 logo on sunglasses

The UV400 logo on sunglasses has the following specific meanings:

Protection wavelength range

UV400 indicates that the lens can block ultraviolet rays with wavelengths below 400 nanometers. Ultraviolet rays can be classified into UVA (315nm to 380nm), UVB (280nm to 315nm), and UVC (200nm to 280nm) based on their wavelengths. Among them, UVC is almost absorbed by the ozone layer, while UVA and UVB can penetrate the atmosphere and reach the Earth’s surface. The UV400 lens covers the UVA, UVB and part of the UVC bands, providing nearly 100% UV protection.

Transmittance standard

The transmittance of the lens for ultraviolet rays with wavelengths below 400nm should be less than 2%, that is, the maximum value T(λ) of the spectral transmittance in this band should be ≤2%. This standard ensures that the lenses can effectively reduce the damage of ultraviolet rays to the eyes.

Comparison of protective capabilities

Compared with lenses marked only as « UV » or « anti-ultraviolet » (typically with a protection wavelength of less than 380nm and a transmission ratio of less than 2%), UV400 lenses have a wider protection range and can more comprehensively block ultraviolet rays.

Verification of protective effect

Sunglasses with the UV400 logo can effectively filter ultraviolet rays and reduce the risk of eye diseases caused by ultraviolet rays, such as solar keratitis, corneal endothelial damage and solar cataracts. If the lenses only reduce the light intensity but fail to block ultraviolet rays, when the wearer’s pupils dilate under strong light, the unblocked ultraviolet rays may instead cause greater damage to the eyes.

Key points of identification

When purchasing, products with the UV400 mark should be given priority. This mark is the core indicator of the lens’s protective ability. In addition, the ultraviolet detector can be used to verify whether the lens truly has the function of UV protection – if the lens can block ultraviolet rays, the UV anti-counterfeiting mark will not be visible during the detection.