How can sunglasses prevent UV400?

UV400 sunglasses contain special lenses with filters that absorb or block ultraviolet radiation, preventing harmful UV rays from reaching the eyes.

Lens Coating: Many sunglasses are coated with a UV-protective layer that stops these rays, even if the lenses are clear or lightly tinted.
Eye Protection: By blocking 99-100% of both UVA and UVB rays, UV400 lenses help reduce the risk of eye conditions like cataracts, photo keratitis (sunburn of the eye), and macular degeneration, all of which can be caused by long-term UV exposure.

In summary, UV400 sunglasses provide essential protection by filtering out UV rays that could damage the eyes over time.