Having a poorer eyesight is not going to make fonts comprised of ten or so square pixels (in a direction) a bigger joy to read. Reading off a low DPI display is not only slower, but it also tires out your eyes faster.
So the ideal (for me) is a large high res monitor sitting 3 or more feet away from me. The first hint you're on this path is when your arms start to be too short for reading books and when you are 100% sure that the gray squiggles on that chip used to have meaning.
I’m not an expert here (I had to look up the Harmon Distance), but from what I understand from other reading about eye strain, this should be rephrased as:
“Reading gets less comfortable if the material is any closer than the Harmon Distance, with some variation depending on age and individual differences between people.”
In particular, there are two factors that make focusing at close distance uncomfortable: (1) you need to flex the ciliary muscles to focus the lens (this is called “accommodation”), and (2) you need to flex the medial rectus muscles to rotate the eyes inward to point at the same spot (this is called “convergence”).
Both sets of muscles start getting strained if you look at a very close object for a long time with no breaks.
Looking at further away objects, even all the way out to the horizon, isn’t really a problem though.
[1] http://oculusrift-blog.com/oculus-rift-faq/492/
No anchors in the page, I'm referring to: "Will the Oculus Rift cause eye strain after extended use?
The Oculus Rift causes very little eye strain, particularly compared to other standard displays or headmounts.
Normally, when you take a break from using a monitor or TV, the idea is to give your eyes a chance to focus and converge on a distant plane. This is a natural position of rest for your eyes.
With the Oculus Rift, your eyes are actually focused and converged in the distance at all times. It’s a pretty neat optical feature."