The military and the police force have unique requirements for safety glasses beyond the scope of chainsaw protection (see video below) but there are still some common parameters.
Apart from the mandatory safety aspect tree climbing glasses need to be scratch resistant and anti-fog. eg Lexa glasses.
In addition, tree climbing glasses must have a lens efficient enough the work in the shade of a tree against the high-contrast sky background (the police use vermilion color lens for this purpose).
Lens quality sounds simple enough, but this is the area where cheap 'safety shop' glasses begin to fail miserably.
Lastly, tree climbing glasses must be comfortable. That is, once you don a helmet with a pair of ear muffs you should be able to wear your glasses all day without the back of your ears feeling like they have been clamped in a vise!
The military and the police look for exactly the same features when they specify their glasses.
Under normal circumstance, military spec glasses stay within 'military' supply lines and are not available for civilian pursuits like arboriculture. Not so with Revision glasses which should be available soon from Treetools.
Have a look at the video below showing how Revision Sawfly glasses compare with other brand (Oakley) glasses.