tianmingwu
I'm a programmer, I look at the computer monitor probably about 8 hours per day. What I did was that I wear a glass with weaker prescription so that when I look at the computer monitor, the characters are slightly blurred but I can still read them. I did this for about 6 month and my prescription went from -5.75, -5.25 to -4.75, -4.25. Actually when I started even with the -5.75, -5.25 prescription my vision is about 1.2 or so.
Unfortunately this technique seems to only work at the beginning. In the months following the first 6 months my vision didn't improve anymore so I stopped it. But I consider spending $300 to knock off 1 point prescription from each eye quite worth it.
By the way I never got any headache from wearing weaker prescription glasses (and I did get headache before when wearing stronger prescription glasses). Actually I found it comfortable to wear weaker prescription glasses when reading, because my eyes don't feel stressed. That is actually the optometrist at Costo suggested to me.
I have since bought more than a dozen glasses from zennithoptical.com, at a total cost of about $300. And by using the technique, the prescription on both of my eyes dropped by 1 (from -5.75 to -4.75). Unfortunately that seems to be the limit of that technique. But I was extremely happy to find a source for cheap yet good glasses. Now I have two normal prescription pairs for daily use like driving, two more pairs for reading (1 for backup for each).
So the cheapest way to get glasses now is to get a prescription at Costco (cost about $40), then just buy your glasses online.