Trillions of photochromic molecules quickly change colour, size and structure when exposed to UV light or temperature increases causing the lenses to darken.
They’re clear indoors and adapt to darken outdoors. Some photochromic lenses also react to visible light and darken even when you sit in bright sunlight behind a window. They are usually available in brown, grey and graphite green.
What are the benefits?
Mainly convenience, but also added protection, as they shield your eyes from the sun’s harmful UV rays when outdoors. They are available in most lens materials and designs, including high-index, single vision, varifocal/progressives and bifocal lenses.
Who are they suited to?
- People with light sensitivity
- Children who don’t remember to swap from spectacles to sunlenses in the playground
- Teenagers (as they typically spend longer time outdoors than adults)
- People who are beginning to develop presbyopia (age-related long-sightedness)
- Outdoor enthusiasts
- People who continuously move between indoors and outdoors