Rustam,

If you're not going to do the ISSF routines then a single pair would be perfect. No need to worry about having the wrong pair with you when you go somewhere and so on. BTW you can get progressive polaroids from Kodak and possibly some others as well, in case you want one pair of spectacles for everything. They used to be expensive in India but are not really all that expensive over here. If you plan on using Polaroid sunglasses (and not your progressives) for your fishing, just buy a set of cheap disposable readers which you would need to tie the hooks to your line, bait the hoks etc and keep them in your tackle case.

And the cataract could be due to any number of reasons. Don't blame the fishing for it.

Yes, UV exposure causes it, but there are other factors like genetics, tobacco use etc that can accelerate the process. I doubt that anyone can pinpoint one single factor as the cause of all cataracts.

Cheers!