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A photochromic lens (sometimes knows as a transition lens) reacts to changes in sunlight or UV exposure conditions by automatically darkening in bright sunlight and automatically lightening when overcast.
Glass Photochromic Lenses
Glass photochromic lenses are solid-tinted, i.e. the degree of darkening can vary slightly depending on the thickness of the lens, as the photochromic substances are evenly deposited over the entire thickness of the lens.
Plastic Photochromic Lenses
The photochromic molecules in plastic lenses are primarily indolino-spironaphthoxacins. These change their chemical structure when they are irradiated with UV and short-wave blue light. Much like a flower when exposed to sunlight, they unfold and cause the lens to change colour.
If the energy level of the UV radiation decreases or – as is the case when the wearer goes indoors – no UV is present at all, the molecules close again. The lens clears and adopts an attractive filter tint.
As the molecules are only found on the lens surface, the darkening process takes place evenly over the entire surface, irrespective of the dioptric power. |
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Photochromic
A lens that changes colour depending on the amount of ultraviolet rays that shine on it. |
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• Find Sunglasses with Photochromic lenses in the Advanced Search
• Find Prescripion Glasses with Photochromic lenses in the Advanced Search
• Find Sportsglasses with Photochromic lenses in the Advanced Search
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