There are settings to make it more readable. Hit Menu on the Remote and go into Settings. You can make changes based on your TV and even more settings if you have a 7 series box.
If you have a 6 series first gen box, you need to call your local Fios store for a newer version. Other than that, set the guide options to SD and it should be easier to read for you.
Another option people seem to be forgetting is Tivo with a cablecard. Yes, the basic premiere unit costs 75 dollars and the monthly fee is about the same as paying Fios for an hd dvr, but you may find that the best receiver to use for people who have vision problems, and many consider it the best dvr on the market anyway. I would rather go that route that switch back to an inferior provider.