I THINK I've got a workaround, with a 'but...'!
Dear Everyone.
OK. First of all I'm not a Mac owner, but my sister's got a Mac Mini which I use sometimes when she's out so she can't catch me using it (people have died for far less!) There's a magnification tool on it called - I think - Zoom. I'm not sure if it's part of Mac or if it's a download. But you can use it to roll over buttons/icons you can't see properly and they're still clickable when they're magnified, I know that cos I've used it like that a ton of times.
I know it's not a permanent, or probably even best, solution but it might work to help out? I THINK there's a way of increasing all font size but I'm gonna have to wait till my sister's around and in an amenable state (she's the one person I know who could make Margaret Thatcher help out with the washing up!)
Still, I hope this helps. I'll be in touch soon with a better solution, I hope.
Yours respectfully
Chris.