"One reason the problem is so pervasive: Unlike words printed on a page that have sharply defined edges, electronic characters, which are made up of pixels, have blurred edges, making it more difficult for eyes to maintain focus. Unconsciously, the eyes repeatedly attempt to rest by shifting their focus to an area behind the screen, and this constant switch between screen and relaxation point creates eyestrain and fatigue. Another unconscious effect is a greatly reduced frequency of blinking, which can result in dry, irritated eyes. Instead of a normal blink rate of 17 or more blinks a minute, while working on a computer the blink rate is often reduced to only about 12 to 15 blinks. But there are additional problems. The head’s distance from the screen and position in relation to it are also important risk factors. To give the eyes a comfortable focusing distance, the screen should be about 20 to 26 inches away from the face. The closer the eyes are to the monitor, the harder they have to work to accommodate to it."