Is it normal to see flashes of light in vision? (staring at screens)

This is the situation. I usually see flashes of black and white (sometimes a colour) in my vision when straining my eyes while working on computers. I can't say how long I've had it, as it nether bothered me too much until I decided to look it up. These flashes are in the corner of my eye usually lasting a couple of seconds. It's the similar effect to itching your eye and seeing dots. I have floaters, but this is different. It's both eyes so retina tear isn't likely. I am quite prone to eye strain and my eyes start to feel dry and tired. Never had sight problems, the last time something like this happened was when one eye was blurred after a whole day of screens and reading. I know that was because of eye strain. Please help.