In reply to stroppygob:
It may be worth going to see a Low Vision Qualified Optician (It's an additional qualification over your "normal" optical qualification - Lady Blue is currently in the middle of the two year course).
There's quite a lot of things that can be done for those with really poor sight that your normal optician may not be aware of.
e.g. there's a funky optical scanner (looks a bit like a computer mouse) you can get which you run over the pages of a book and it brings the text up on any screen. Park the elderly person a couple of feet away from a huge flatscreen telly and they can have letters bigger than their head if they want... Obviously less extreme magnification is possible too!
However a LV Optician wil be able to look at the visual acuity and the condition/disease/etc the person has, and work out what can be done to make their life easier, whether it be medical, occupational (a surprisingly large number of elderly people with failing vision insist on reading in poor light, which does not improve things), or technological (e.g. the mouse scanner above).