I got into a situation last night that started me thinking about this. Very cloudy prior to sunset. Skys clearing at sunset and I'm fishing with no eye protection when I can't see the fly! I normally use amber lenses and it was just too dark!
I don't like the idea of carrying multiple glasses for different conditions (but will if I have too). I also cannot sell my soul to the devil to cover the cost as I've already done that for other gear!!
Any suggestions/advise?