Glasses

A pair of glasses is an item commonly wore by people with weak eye sights. Several of them wore those things for cosmetic purposes.

Canon
Homura Akemi wore them when she's a civilian and a Magical Girl (till the 3rd loop) , Mirai Wakaba also use them, but she somehow disposed it after she became a Puella Magi, while her fiancee friend Saki Asami, currently wears them in civilian & Puella Magi modes.

Fanon
Hilda Adams had owned a pair of glasses before she had healed her eyes with magic. She occasionally (but not frequently) uses them for reading stuff. Jinna Asumi also uses them, trying to read several complex words. But she's still illiterate.

Trivia/Notes

 * And no, wearing them does not make you smarter. Unless you want to stereotype hard.