However, high brightness contrast is the definition of glare which is a common cause of eye strain. White background normally covers most of your screen’s surface to contrast with black text. This post should help you solve your screen brightness and text-to-background eye strain problem principally by showing you how to change background color and text color in Windows 7 (affects Word, Excel, and other MS Office programs), Adobe Reader, Internet Explorer, Firefox, Chrome, … Windows 10 users see this post. Either way extended computer screen viewing will likely cause eye strain (eye fatigue or computer vision syndrome). How to reduce screen brightness is important if you have light sensitive eyes (some level of photophobia), or if you use your computer in dimmer environment.