Can you mess your vision up if on phone or electronic device a lot?

I'm on my iPod touch allll the time, everyday, mostly because of social networking %26amp; blogging. Sometimes my eyes feel weird. Is it because of being on it so much?|||Your eyes can sometimes hurt if you look at a screen for too long, such as a computer screen or a television screen because you are focusing on one object for an elongated period of time. To stop this from happening, take a break every half hour and just let your eyes focus on things far away and up close.