As such I've started using my 3m 6800 which I'd normally use for spraying. I don't think I'll go back to using the half mask much now. Absolutely no chance of stuff getting my eyes etc now as I hoover the top of the mask and my head before taking it off. Lens protectors are quite cheap off ebay too which I change periodically when the lens starts getting too dirty/ scratched.
Have you got a link to them? I just had a search and couldn't find any.