Eyewear equipped with Transitions lenses® incorporates special photochromic lenses that have the ability to adjust the tint level. These lenses transition from a clear and transparent state to a darker shade resembling sunglasses. The tint shift occurs gradually, and there are multiple stages of tint coloring and darkness intensity. These lenses “activate” in response to sunlight, specifically the sun’s UV rays.
On average, it takes between 30 seconds to a minute for the lenses to darken completely. However, when the lenses are no longer exposed to UV rays, it may take several minutes for them to fully return to a clear state.
The degree of darkness is determined by the intensity of UV light, the time of day, and the direction of the sun. Various factors such as extreme temperatures, UV exposure, and the materials used in the lenses can also affect the level of darkness in photochromic lenses.
It’s important to note that the effectiveness of the transition is not dependent on the brightness of the sun, but rather on the exposure to UV rays. Therefore, even on slightly overcast cold winter days, the transition of your lenses will still work properly. The main difference is that in colder temperatures the darkening process is slower, and it takes more time for the lenses to transition back to lighter shades. These are because the molecules responsible for the transition slow down in colder conditions.