My wife and I discovered the Bates method quite a long time ago, possibly put on to it by my wife's Mother, unless she got it from us; can't quite remember. Anyway, my M-I-L practised the exercises all her life, and never wore glasses....but needed a magnifying glass to read certain things, so...
Anyway, we found it slightly helpful, especially the "palming", but I don't think we found it of much practical use in the long run, to be honest. Along the way, we also discovered another book about vision improvement by a man called Harry Benjamin. His book has a similar title to that of Bates, and his method is based on that of Bates, with the addition of changes to diet and lifestyle - Bates was a Naturopath.
http://www.amazon.co.uk/Better-Sigh...=sr_1_1?s=books&ie=UTF8&qid=1295816937&sr=1-1
My wife was short sighted and I was long-sighted, and like most long-sighted people seem to do, I started suffering the symptoms of presbyopia, although probably a bit earlier than most, probably around late 30s. This made reading close up difficult, and eventually all reading, and in the end, I gave up and got reading glasses, and later on, Varifocals. One thing I learned about presbyopia ("old sight") is that as well as affecting your near-vision, it also can affect your distance vision. I was shocked to realise that I could no longer read a numberplate at 25 metres, and from then on legally had to wear glasses to drive.
I would say that reading glasses and the varifocals have made my eyesight worse over time, but what is the alternative? (I wouldn't risk laser surgery, even supposing it was offered for my condition, and I couldn't live with contact lenses). Opticians would not agree with me, naturally.
I think that technically, short-sighted persons also develop presbyopia, but it doesn't affect them in the same way, and may even reduce their short-sightedness slightly.