As someone mentioned, the condition of one's eyesight is more important than age. But I get the drift of your original post. I'm 62, and don't see as well as I once did.
With displays vis-a-vis "aging eyes", the specification to look at is "dot pitch" (also referred to a "pixel pitch" or "pixel size").
It seems that with the coming of the "high definition" age, dot pitch is getting smaller on many displays. This isn't a problem for the younger folks who still have all their vision. It _is_ a problem for us older folks, though.
A possible solution might be for you to consider a display that has "less than modern" resolution -- call it "medium rez", for lack of a better term.
There are displays like this out there. One version that comes to mind are a small number of 27" displays that are 1920 x 1080. This is considered "standard resolution" for a _24"_ display (not 27"). So the overall effect is the same image you would see on a 24" display, just "blown up" a bit larger (because the pixel size is larger).
Here's an example of what I'm referring to:
http://www.amazon.com/Samsung-P2770...NC00/ref=sr_1_1?ie=UTF8&qid=1323959178&sr=8-1
There are a few others, as well. The one in the link above also comes with a built-in TV tuner (although it is not specifically designated to be a "tv").
Many younger folks would look at such an image and proclaim, "ugh -- it's too grainy". But for someone like myself, the image looks just right!