Auto-darkening welding masks block UV and IR all the time [1] so you're protected against things like arc-eye even if it fails to darken. Also, masks generally fail-safe (to darkened, e.g. for flat batteries) and presumably this welding microscope is designed to the same standard.
the 'eyeball full of sand' can last for several days, and really interfere with your normal functioning. that and the greatly increased acceleration of cataract development means really dont look at the blue light.
