Phone help for straining eyes

Hi Apple core, I was wondering if I could get a bit of help with a problem my mum is facing.

Basically she has an iPhone 4S, but is finding it very difficult to see things like web browsing and texting on such a small screen, testing things out on my iPhone 5 seemed just as bad; even with all the accessibility features on both iOS6 and 7.

She really likes the screen of my brothers S4, but doesn't particularly want to make the switch to Android or Windows Phone, and using a 3G iPad or iPad mini is out of the question because of a lack of VOIP / calling / texting apps that work in Australia.

Any suggestions are welcome and appreciated, thanks :)