Id really advise against using glasses at TTAC for force on force airsoft, CAPS sure but you aren't being shot at.
At paintball field like Flagraiders, we are obligated to use paintball goggles, but not the full mask, I only use goggles for outdoor; but at an indoor place like TTAC or Sgt. Splatters I'd recommend using a full face mask, it's just not worth taking a chance.
For Milsim OPs at private fields I use shooting glasses, as the engagements are seldom up close and the people that attend know how to play safely so I'm not too worried.
There's a game at TTAC3 next Friday you should check it out (if you haven't signed up already) get to meet some members from the local community and all thy good stuff.