Reactions is a brand name for photochromic lenses. When exposed to UV light, photochromic lenses darken and then return to a clear state when the light source is removed.

They are designed to darken to just the right level depending on available light.Photochromic lenses block out 100 per cent of harmful UV rays and many people who already require glasses may find them more convenient. This is because they can benefit from having glasses that support their normal prescription and offer sun protection without having to switch between two different frames.

How long do photochromic lenses take to work? Photochromic lenses begin to darken immediately when exposed to UV light, providing substantial protection within the first minute. After this, lenses will continue to darken gradually as the amount of light varies.The lenses typically take slightly longer to return to a clear state, but are noticeably lighter within a couple of minutes and almost completely transparent within five minutes.Are photochromic lenses affected by the weather?

Weather conditions will have an effect on how quickly photochromic lenses change colour. As they use a thermal process, the lenses will not achieve a high level of darkness when it is very hot. On the other hand, they will go very dark in cold weather. Once they are away from UV light, cold photochromic lenses will take longer to return to a clear state than warm ones.

Can I wear photochromic lenses while driving? Windscreens block UV rays pretty effectively, which means photochromic lenses will not work as well in a vehicle. Are there any disadvantages to photochromic lenses? While photochromic lenses are often seen as more convenient than swapping between different types of glasses, some people do not like to wait for them to darken and clear.