In addition, while attempting to view the screen more clearly users tend to hold their heads in unnatural positions which contributes to neck and shoulder pain. When any of these symptoms appear they inevitably lead to decreased visual efficiency and an increase in typing errors. Eyestrain is primarily a result of overworking the muscles of the eyes. This can happen in four ways. This causes the user to exert extra effort to keep the eyes focused on the screen.
Glare is another common factor in eye muscle fatigue.
Like a TV screen, if there is a glare on the monitor the eyes have to work harder to discern an image on the screen. Thirdly is the position of the monitor. In their natural resting position the eyes accommodate a field of vision straight ahead and slightly down. If the monitor doesn't fall in that field of vision, muscles must continually work to hold the eyes differently. The final way to overwork the muscles of the eye is to use rapid, repetitive movements such as darting your eyes between a source document and the screen.