Hi, in the (dim and distant) past I had glasses frames supplied directly by Draeger (for the Panorama Nova), which I then brought to Specsavers to be measured / tested. (Specsaver also advised that they had a number of alternative frames that could fit the mask.) They asked for a mask which did not have the safety visor fitted so that they could get an accurate distance of the glasses frame from my eyes / face. My employer had an "old / disused" mask that all of us spectacle wearers could bring to the opticians. When the frames were glazed, Specsavers confirmed the lenses insitu in the mask with a final eye test. I assume that are other opticians who offer a similar service. I have no details for the MSA mask.

I've specified the same ones as Descarte but these are for a Sundstrom mask. You will need ones that fit the mask you are using and this is best found out from the supplier.