After I turned 35 (a while ago) I discovered that my eyesight had deteriorated to the point where I need glasses. I only need glasses for distance, so I wear them to drive, watch hockey and to see if the women on the other side of the bar are good looking. At the same time, my near vision has also fallen off. I can no longer focus as close as I used to be able to.
My first mask had corrective lenses from my old snorkeling days, and that was great for seeing things at a distance, but it really messed up my close vision.
When I first started diving, I had some trouble reading the rental computers. The characters were small, and a little blurry. However, I was able to read my buddy's dive computer easier than I could read mine. He has an Oceanic Data Max Pro Plus whatever-the-heck it is. The readouts range from big to really huge. At the time it was the largest readout available.
I tried the little "guage readers" inside my mask at one point. They didn't work real well, and kept falling off. As described by others, they work for some people, not for others. (I can't stand my above water "progressive lens" glasses either, so the problem rests with me primarily.)
I bought myself an Oceanic Versa Pro computer and then an Aeris Atmos II as a back up (essentially same basic computer). They have such large characters that I am able to read them just fine. Other manufacturers now have large characters, but check out the size of the Oceanic displays.
Also, when I am going to dive in Monterey, I don't wear my glasses in the morning before I dive. I find that I can see up close a lot better if I have not worn my glasses at all that day. Rested, uncorrected eyes seem to be able to focus closer for me.
Also I got a second mask, and this one was left with the standard plain glass lenses. For most of the Monterey diving that I do, the things that are within the range of visibility are close enough that I don't really need the distance correction of the old mask. Mostly in Monterey we get "up close and personal" with the rocks etc. I use the prescription mask occasionally in Florida or Cozumel where there are a lot more things visible at greater distances.
Between the large computer readout and the relaxed eyes, I am able to read my computers just fine.
There are companies that make prescription masks and even bifocal masks or replacement lenses for many popular masks. I have a link at home to a good one in southern California, but I am sure that there are others on the web.
You gotta find what works for you, but consider Oceanic.
Just sharing my thoughts and experiences,
Wristshot