I never really noticed this problem with my guardian, but I can absolutely see how it could occur. Just like people can complain about dry mouth after dives where you are constantly exposed to dry air from a regulator, you can have dry eyes from constant exposure to dry air filtering through the mask. I don't think that demand vs positive pressure would change this much, either, as breathing would trigger the demand, and would result in regular turn over of the air inside the mask. Also, the guardian seems to be more of a quasi-positive pressure mask. If you break the seal, it will free flow the reg. Finally, the reason you don't need antifog in the full face masks, including the guardian, is that some of the inhaled gas is directed over the front faceplate. The same thing that drys the inside of the mask will also dry your eyes!
Your best bet is to try some lubricating eye drops prior to putting on the mask. You may want to give that a try topside before taking them for a dive, though. Some of the "long lasting" drops have an oily base to them and can mildly affect your vision. Not a problem if using them overnight, but an annoyance if you are trying to look at all the pretty fish underwater.
Your best bet is to try some lubricating eye drops prior to putting on the mask. You may want to give that a try topside before taking them for a dive, though. Some of the "long lasting" drops have an oily base to them and can mildly affect your vision. Not a problem if using them overnight, but an annoyance if you are trying to look at all the pretty fish underwater.
