German to English Tech/Engineering Engineering (general)

I'm translating specifications for eye protectors.

The term "Sichtscheibe" crops up on a number of occasions and is used to mean an material through which the person looks. For example:

"Augenschutzgeräte gelten als gebrauchsfertig, wenn sie mit Sichtscheiben ausgerüstet sind."

My problem is that I can't find a catch-all word in English. In some cases, "lenses" seems the most appropriate word, in other cases, it is referring to "visors" that cover the entire face, the front plate on goggles or the window in welding masks. It's also used in relation to screens that can be placed between the operator and devices like lasers.

Any ideas?