I sit the same distances than you. And that's just were my myopia kicks in too. If I don't have my glasses on, I can't read my laptop or my external monitor at all unless I squint and look at it from closer up.
And still, I find anything under 160 PPI+ to be too low. So frankly, I don't know about your perfect eyesight...
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No, they won't. They'll look the same as they do now, with sharper text.
A 100x100 image will look the same blown up to 200x200 on this thing than it does at 100x100 on a non-"retina" MBP.
Basically perfect, as tested for my PPL. So unless those doctors got it wrong
No glasses, 20/20 vision, etc...
There is a difference between being able to read something at high res and being able to read that high res for hours on end. The latter being the important one for the health of your eyesight.