The lenses of photochromic sunglasses lighten or darken in response to the lighting condition. For example, the lenses will lighten or darken depending on the amount of exposure to UV or ultraviolet radiation. Lenses tend to return to its clear state without the UV exposure. On the contrary, it will turn to darker tint when exposed to the heat of the sun.
The idea behind this mechanism is similar to that of a photographic film. The film darkens when the silver based chemicals react to light exposure. However, photochromic lenses do not darken permanently like photographic films. The glasses return to its lighter shade once the light level goes back to normal.
With the advancements in technology, the photochromic lenses today come in different categories as far as sun protection is concerned. The best lenses have high speed activation time. This means the lens can change from light to dark depending on the exposure to UV light at a very fast pace. These light adjusting sunglasses also come in fashionable designs and frames.
So now that we understand a little bit about how photochromic sunglasses work, it is time to know how it benefits us and what its flaws are.
- Photochromic lenses can provide the right amount of protection for different light conditions.
- These sunglasses are efficient for people who are constantly exposed to different temperature and lighting. Since they adapt well to different conditions, switching sunglasses is no longer needed.
- They have 100% UV protection to keep your eyes away from damages.
- Less advanced models take longer to adjust from light to dark and the other way around.
- They may be less efficient in cars where the windscreens block most of the UV light. Although there are specialist photochromic lenses designed for driving that you can use for this purpose.