sitting infront of the computer causes eyes pains. remedy for this is after sitting half an hour infront of the computer look at the garden or any other position for five or ten minutes,other remedy is in morning or evening close your eyes and count 1 to 10 then open the eyes and repeat it. This is very good for the eyes.
Because the eyes, just like any other muscle, gets tired after prolonged use. If this starts happening, then get away from your computer and rest your eyes and then go back when they are comfortable again.