Stan wears tinted glasses maybe?
I could see Stan being dyslexic -- I remember one kid at my school used to wear yellow or orange tinted glasses when he was reading in class. I do believe Stan would think he was sooooo cool and unique for wearing these. He probably does, still, sometimes, although he doesn't wear prescription lenses. And he's bad at keeping up with stuff that is good for him lol. But for sure he loves the whole Elton John, cool coloured glasses thing.