Omg, 8-12 hours a day
You need to be giving us tips, xtra. Have you got some sort of poker regimen going? Do you eat nothing but protein shakes and power bars?
Seriously though, if you're gonna play that long, the first thing I would do if you haven't already is turn the brightness down on your monitor. It should go a long way towards keeping your vision. That or get some shades.
