RE: sunglasses
As a fishing guide I can tell you without a doubt that the Optically correct glasses are much better on your eyes......the quality isn't so much in the ability to see into the water.
The quality is in the comfort on your eyes,and brain, and their ability to stay that way(scratch resistant).......some of those cheap ones will have you cross eyed in no time flat.....I'm not going to trust my vision to a $8.00 pair of glasses anytime soon.
I took a cheap pair to my eye doctor once to see what he thought......he said "Yeah they're great!.....do they come with Excedrin?"
For the casual angler you might not notice a difference, but for the person on the water 10-12 hours a day in all lighting conditions....you'd BETTER have a good pair.
And make sure you are using the right tint for the type of fishing you are doing, or you aren't getting the full advantage.
I use "Action Optics" glass lenses in a Brown tint for river/stream trout fishing.
They're expensive but worth it to me.