Hello.
Maybe you can try changing some options in the settings of the game to help you out with this.
In Main Menu > Options > Video:
Turn Particle Effects to Low
Turn Blur Quaity to Low
Turn V-Sync to Off (To test how it feels nicer in your eyes)
Turn Frame Rate Cap to On (To help with motion sickness if it bothers you somehow)
In Brightness, adjust it to your liking and to what is more comfortable to you.
Depending on how bright your monitor is, you might want to adjust that too.
Also, probably you should try to play with your head as far from the monitor as possible, because that also tire the eyes faster. Make pauses while playing (if 1hr session, do a 20 mins pause, etc, also this really depends on you.)
I really hope this help you. Cheers and good luck. :)