Eye Strain Simply overusing the focusing muscles of your eyes can cause eye strain which often results in a headache. Our high tech world has improved our lives considerably, but small-screen texting and web browsing often causes strain on our eyes. Words and images on a computer screen do not have well-defined edges, as they are made up of several small dots, or pixels. The eyes cannot easily focus on pixels, so they must work harder to see the computer screen clearly. When the eye muscles become fatigued, a headache often develops around or behind the eyes.