When using an ubumask with glasses, it is best to fit the mask first
to get the correct fit with no seal leakage, then place the glasses on
the mask. It is really dependent
on the seal of the mask. A good seal around the nose and cheekbone
will mean no leakage in that region which equals no misting. This is
how/why glasses get misted up
on the inside of the lens. In our experience most glasses wearers
manage to figure a way of fitting glasses with a mask without them
getting misted up.