I've seen some prescription face shields on scba air packs in the oil patch. Those face shields can work with filter cartridges depending on the brand. I would ask your optometrist or oilfield supply store.
I don't wear glasses but I've watched lots of guys struggle with wearing glasses and face shields and it takes a lot of practice on how to breathe properly to keep them from fogging up. But in some cases like shovelling grain it's almost impossible to wear glasses in cold weather.
Have you tired RZ Mask? They have two masks, one made of neoprene and one made of mesh. They are extremely comfortable and effective. Both come with disposable filters that block 99.9% of airborne pollutants sized .1 micron or greater. Filters last around 60 hours of exposure and are cheap! A mask runs for $29.95 and a pack of 3 filters is $6.95. They have the exhaust valves preventing condensation build up and glasses from fogging. Check them out at rzmask.com.
We have a full face mask that has two cartridges ( one on each side ) and there are ones for NH3 and then another for dust etc but as I wear glasses its horrible to wear I find since my glasses fog up right away and also I sweat something awful if I am doing anything while wearing it or if its in warmer weather. Its actually the very same mask that the company that comes to fill our NH3 wears when they connect/disconnect the tanks and also when they are filling the bulk tanks for gasoline or diesel if they feel the need. I'm not sure what brand it is though as I'd have to dig it up but imagine that or another equivalent unit is what your local safety supply store would sell regardless. Try one on first if you can for a bit, then make up your mind if its for you.