If you ever have had the unfortunate experience of leaving your plastic
in the sun or wondered why the colors of your clothes fade away, then
the technical term to express your misery is Photo-degradation.
This is the other extreme of a reversible reaction where UV light from the sun break break down the chemical bonds in the plastic and clothes (called chromophores) and eventually leads to fading of the colors in the object
As any user of one of these Photochromic lenses will tell you, there are some aspects of these lenses that still need to be improved
- The chemical reaction rate depends on the temperature of the surrounding. This means that on a sunny day if you are in a really warm climate, the lenses will adapt faster than if you live in a cold climate
- Most car windshields block UV light to some extent and therefore these lenses are not effective when you are inside the car.
- They do degrade after a while. Most of lenses do degrade having been used after a couple of years and need to be changed.
But having said that Photochromic lens are indeed a really cool piece of technology.