I’ve noticed that working all day, every day on a laptop puts a strain on my eyes; on the subway home it takes about 20 minutes before I’m fully adjusted to far-vision again.  

Deciding to do something about it, the past few days I’ve been sure to use an external keyboard and mouse so that I can get the screen further from my eyeballs, and it’s made a HUGE difference (note the use of caps to prove this point).

Hopefully this is already common sense for long-session laptop users.