Why have humans in their evolutionary path not select out people with severe nearsightedness nor farsightedness? They did not have glasses for correction until recent times.

What a great question. You would think that saber tooth tigers or other predators would have picked off all the proto-humans before they had the chance to pass on their nearsighted genes!

The fact that there are a growing number of myopes (people with nearsightedness) in the last century supports the theory that myopia is in large part not primarily a genetic condition, but rather an adaptive problem, possibly caused by civilization's confining children to indoor rooms and concentrating on near tasks (like reading and writing) during the growth years.

There are two vision problems, though: the 1) distance vision problems like myopia (nearsightedness) and astigmatism, and 2) the farsightedness of middle age (loss of up-close vision). The latter problem was never much of an issue until the last century or so because life expectancy was so low that most people had died off by the early 40s when presbyopia would have become a problem!

_Written by J. Trevor Woodhams, M.D. - Chief of Surgery, Woodhams Eye Clinic