I have been using gunnar glasses (untill recently) and they do give comfort to the eyes for long pc,tab,gaming sessions. Keeps the eye moist,less tired( also less headaches for people who wake up with a headache after a night gaming session). But the yellow tint takes something away from the graphics.(especially lightening and ligetening rays)
After i stopped using them about a year back or so ( i still have them in my room all the time), ive been playing in well lit enviroment(even at night). I do meditation,pranayama regularly .that helps to reduce eye strain and stress caused to eyes by continous gaming.
Also try to blink lot more in between gaming sessions( esp when spare time during matchmaking or in lobby) or a better thing to do is to get up and look at distant objects(esp something like trees which has soothing effect on eyes) in between gaming sessions.
Another good practise is to set the brightness level of tabs,phones,monitor tv to a comfortable level and not at very high. Very high may give you better gfx but at the cost of headaches and constant eye fatigue.