How Does Your Computer Affect Your Vision

Today I have been sitting in front of my computer and taking small breaks in between.I don't feel any problem while I am reading or typing here ,but when I am away from it my eyes are itching a bit. Again, when I am back in front of the screen ,my eyes cooperate like my best friend.I would think this is opposite of what should happen. Do you think using the computer for a long period affects our vision ? Has this happened to you ? What do you do about it ? How important is the monitor with regards to our eyes ?

[question posted by bluewings]

responses and comments: