Computer glasses are critical for me. Without them I can hardly work on a computer for more than a few minutes before my eyes start to bother me.<p>When I first got prescription computer glasses, about five years ago, I tried to use one set of glasses for both reading and computer work, so they were calibrated to focus at about 21" (roughly halfway between book reading distance and my monitor distance). It was a major improvement for my computer work, but it was noticeably less than ideal for reading.<p>So last year I just got two pairs of glasses, one focused at 12" for reading books, the other focused at 30" — the more or less exact distance from my eyes to my monitors. This was a <i>huge</i> improvement for me. Text on the monitor was so sharp I could hardly believe it (still is, but now I'm used to it), and my enjoyment reading books was vastly improved too.<p>I highly recommend prescription computer glasses if you're getting up there in years.