Importantly, are Harold's glasses just for show?

I'm following astolat on tumblr now, and she reblogged a PoI AU where Harold's like 30, and John his 20 year old soldier bodyguard for a bit, and I'd usually not even click on that premise, cos people generally change so much in 20 years they're hardly the same characters, except, you know, astolat, and I'm a sad fangirl, so I read it, and liked it well enough *shrug*

Oddly, the bit I got hung up on was John handing Harold his glasses, and Harold was all squinty without, and that reminded me that I'm not convinced, canonically, that Harold needs glasses at all. ( Cut for discussion of scene in very recent ep, in case people haven't seen it yet )