OK I have to step in here on this discussion since I am an eye  doctor.  Loss
of reading vision is called presbyopia, not  farsightedness.  I just turned
40 and have been low carb for 1 1/2 yrs and  paleo for 8 months.  I'll see how
my reading goes as the years go on.   Typically anywhere between 42 and 46 is
when the lens has hardened to the point  where your "arms aren't long enough"
any more to see small print up close.   I don't know if any of my patients eat
paleo so I can't comment yet on the  diet/presbyopia connection.
Lisa