Some of the Oceanic computers have really large numbers, and they are pretty easy to read, even for people with bad vision.
My buddy has an Oceanic Data Max Pro (or something very much like that). It is air integrated and chock full 'o bells and whistles. It also has what were the larges LCD numbers at the time it was introduced.
When I was still renting, I could read his gauge easier than my own Prodigy or Suunto Favor.
When I bought, I opted for the Oceanic Versa Pro (and an Aeris Atmos II) which is simpler, no air integration, and has numbers just as big. It works well for me.
Another alternative would be to get a prescription mask, and you can get them with "bifocal" or whatever custom RX you need, it will just cost you $. A recent dive magazine listed two ads for RX Masks, one was $189 the other $119.
None of these options are cheap, but it is a long term investment. Well, expenditure anyway.
Wristshot
PS: I tried the little stick on lens device for seeing close up. They cost about $35, came off too easy, and didn't work for me. However, they do work for some people.