Are you new to Microsoft Office 2013 and find it flat and stark white? I too felt those same sentiments until I changed the Office Theme to dark gray which has reduced my eye fatigue! Office 2013 has three options: white, light gray and dark gray. Office 2007 and 2010 has blue, silver and black Office Themes for the PC, which I really miss!
Customize the setting that best relieves your eye fatigue–change it as often as you like! Read the tip that is compatible for both PC and Mac. May your eyes feel better at the end of your day! Cheers