When the sunlight changes, the tint changes. The science behind it is complicated but the result is as simple as that. Each Photochromic lens contains millions of organic molecules that react to UV light. When exposed, the molecules change shape, absorbing light and making the lens darker. When there is less UV light, the opposite reaction takes place and the lens tint becomes lighter. Like all of our lenses, our Photochromics are impact resistant and optically correct with 100% UVA, UVB, UVC protection.