>>302875760
I use lenses for the Index. 

Never tried the Index without the lenses, though, so I can't compare, but I feel at peace in my mind when wearing the headset because there's no possibility for me to directly scratch the actual lens. It's a bit annoying that there's a little opening that allows for, for example, dust to rarely fall onto the actual lens, but most gets stuck on the prescription one instead. Makes cleaning very easy. They're also easy to install and deinstall.
I always worry that my Index glare comes from the prescription lenses, but that's probably clueless superstition on my part and just part of the Index.
I don't remember whether they get foggy. Might've happened once or twice, but if so then so rarely that I don't remember.