Used to be 20/20 w/ an astigmatism and never needed glasses. After working w/ computers for about 7-8 yrs, I went to the eye doctor to complain about my eyes hurting. Strangely enough I still have 20/20 vision yet, due to eye strain, my eyes have trouble compensating for the "fuzziness" of fonts; the doc said that my eyes try to smooth them out. I got a mild prescription and it's great. No worse after 3+ years.

Coupla protips: * Don't code on a white background - hurts/strains the eyes moreso than a gray bg

* Buy a great monitor - $100 more in cost isn't worth saving if you lose x% of eyesight or have pain.