My approach is similar to this, and I have training partners who I trust to keep metal training knives below the neck. Of course, accidents happen but wearing eyepro on the mats is problematic enough that I rarely do it. New students can be spastic and unpredictable, so I have a pair of my favorite safety glasses in my gym bag. Fogging is a problem even with the built-in anti-fog treatment, so one student drilled a bunch of air holes in his.
Radians RS1-11 Rad-Sequel Rubber Tipped Lightweight Glasses with Clear Anti-Fog Lens
https://www.amazon.com/gp/product/B001GRO9DA/