[charli (OP)]

Shelley would like to know:

"How do eye glasses change to dark in the sunlight?"

Can you shed some light?

[Zer0]

Hello Shelley!
🙏
& Thanks for your Question.
🤓

Eye glasses that get darker in Sunlight are Photochromic Lenses.
(Popularly known as Transitions Lenses)


I've learnt that these Lenses have a Special coating on their surface.

The special material on the surface reacts with Sunlight by absorbing it & change their shape.
(Darken)



But this process is Reversible.

Once out of direct Sunlight, they retain their previous shape.
(Lighten)



P.S. - i got all the info from Wiki.
https://en.m.wikipedia.org/wiki/Photochromic_lens
😎
(Just began learning Chemistry, hence cannot clarify or further explain chemical changes of molecules & compounds)