Bear with this explanation and maybe it will be helpful
I've worn a contact lens since 1980 so that I could use fish finder glasses and that was a good system. However I realize not everyone can or likes to wear a contact. I always had to carry a pair of reading magnifiers with me because the contact corrected my vision for seeing fish out there in the river but once I was working up close with a knot I had trouble focusing.
Problem was that with glasses I could see at distances fine and by looking under or over them my up close vision was great too. So where's the problem? If I wanted Rx polarized glasses I would still have to carry a pair of clear lens for low light and after dark......... Carrying an extra pair of glasses or sunglasses is just one of those things that works great until something goes wrong. So I stuck to my long wear contacts and readers until 2 years ago. In the meantime I went through plenty of readers, broken & lost were the primary causes for replacement.
2 seasons back I discovered that I could get a pair of very small Rx in a frame by Oakley. Super light & small enough to look over or under when tying knot etc. The real surprise was that I could get a photo chromatic lens with polarization layer also. The polarizing quality for spotting fish is not quite as good as a pair of dedicated fish finders but they work well enough for me to be able to spot fish and see my flies on the swing in most situations. They are clear when it's dark or raining but even then the polarizing properties work. No 2 pair of glasses, no readers, and I wore them on all the fishing trips last season.
If you are going to spend a bunch of money on a pair of glasses this may be something to consider. They are good for fishing and good for everything else also.
If you are going to fish salt water then a pair of Cocoons like Fred suggested will get it done and you can save a bunch on your Rx glasses.