When you are tired and/or are working in an environment with lots of artificial heating. The resulting dry and possible sore eyes can now be referred to as "Dryballs".
This is an affliction often suffered by contact lens wearers and those that like to party...a lot.
"My wife kept me awake all night and now I'm at work, staring at this computer screen for eight hours with the heating on full - I've got a major case dryballs!".