Well, seein' as we're all bein' unscientific an' unedumacated about it ..... when I wanted an answer for this in the '70s, I went to an optometrist who fitted me out with Carl
Zeiss lenses. Yup, the same mob that make, amongst other things, the lenses fitted to professional cameras. An' das good enough fer me.
The beauty of having sunnies made up is that you can pick whatever frame you want. Sometimes, I'd get a cheaper frame, such as a Rodenstock, but hell, you can get any sort you want.
As was mentioned earlier: what price yer eyes?
An' das ma 5o cents worf!