I was certified on full-face respirators for almost 40 years. By the time I started using them in 1980, there were no longer individual "eyes" on them, and you could, presumably, see much better out of them. Alas, you still had to get a good seal between your face and the rubber of the mask, and at best they were merely uncomfortable unless you had to do some actual physical labor while wearing them, in which case they were excruciatingly uncomfortable. On numerous occasions I could literally pour the sweat out of my mask when I was done working. Powered air purifying respirators (PAPRs) were not only more comfortable but provided a much better protection factor than the masks. Still a pain in the butt, though.

In the US military an important part of everyone's basic training is going into the gas chamber (a small building) and removing the mask to feel the full impact of CS. It's not pleasant, to say the least.

2023 minus 1942 is ... uhh ...

I found myself in a gas demonstration using real people (i.e., me). By that time the masks looked less like Harpo Marx and more like grasshoppers.