I asked my optometrist about the risks associated with looking at a computer screen all day, every day, and he said there was absolutely no chance it could affect your eyesight.
Asked the same thing, when she asked me how much time I spent and I told her 16 hours a day, every day - she wasn't surprised, everyone is in front of PC's all the time now. Got the same relpy as you.
Still have perfect eyesight too and I've been on computers for more than 10 years obsessively.