I have he vision problems too, and that was the main reason I got the Reader, as they advertised it as helpful to visually handicapped people by offering larger fonts. Many of the purchased books I got have a problem with the largest font in the landscape mode far too small for me to read comfortably.
Repeated calls to Sony have resulted in absolutely no help, except one time when I insisted, they did give me a credit for one book. It was far too much of a hassle to repeat this for each one that gave me a problem.
Therefore, I am going to get either the Cybook Gen 3 or the Kindle. As I understand it, the Cybook, like my old Rocket eBook, lets you load any font and type size you have on your computer and use that. The Kindle has six sizes of type, the largest being 20 point.
It is too bad Sony misrepresented this factor and also fails to do anything about it. While I'm waiting to buy one of the two new ones, I just use the free books which can make any size I want. When I get one, I'll sell the Reader.
Some posts here has suggested that this is a problem in the way the publishers format their books, and thus differ among them. However, if the two ebooks mentioned above, and even the really old Rocket eBook could make it easy for visually handicapped people, it is idiotic that Sony does not care or do anything about this.