There is one tool no fisherman should ever be without. Sunglasses.
I have type 2 diabetes and have to go in for an annual eye exam, and my doc told me that I have zero sign of cataracts - I'm also 62 and have a genetic predisposition to them. I've worn sunglasses pretty much every time I've gone outside since I was a teen. I started because of sensitivity to bright light.
Wearing sunglasses is easy. Keeping up with them is the hassle. I lose sunglasses. I sit on and break sunglasses. I drop them into deep water. They drift off and end up under car seats or distant trees. I love sunglasses, they are the best things in the world, but the average life-span of a pair of sunglasses with me is about two weeks. That's one reason I don't buy the expensive ones - I have bought expensive ones, and they seemed to "go away" faster than the cheap ones do. Probably not really any faster, just more painful.
I also don't buy expensive ones because there's really no point in it as far as I can tell - unless you are trying to make a fashion statement - which I'm way past doing. The best and highest quality lens is a wonder to look through for about five minutes. Then sweat gets on the lens and they might as well have cost you 10 cents. Sweat, dust, water spray, bug spray, beer foam, whatever...something always gets on them and distorts the view. At that point expensive lenses have no advantage to my way of thinking.
In case you've been living in the bottom of a lead mine, UV radiation - which is an integral component of sunlight - is bad for your eyes. UV radiation is a very dangerous and harmful, not to mention a nasty, thing. How nasty is it? UV radiation has been linked to cataracts, macular degeneration, pingueculae, pterygia and photokeratitis. Those are bad things to have. Anything as hard to pronounce as those are can't be good. Look em up on google - scary stuff.
Cheap sunglasses (sounds like a rock song for some reason) still need to be good sunglasses. Cheap is a relative term of course, but in the grand scheme of things you need sunglasses that do two things. The need to block 100% of UV rays and also absorb most of HEV rays. HEV = High Energy Visible. I'm not going into a light wave physics lecture - just look for the letters and the words "protects against" or "blocks".
Children especially need to wear sunglasses. The damage caused by UV is cumulative. Some studies suggest that half of our total exposure to light occurs by the age of 18. Children's eyes are even more susceptible to retinal damage from UV rays because the lens inside a child's eye is clearer than an adult lens, allowing more UV to penetrate deep into the eye. Make sure your kids and other loved ones are wearing sunglasses when you take them fishing.
Sunglasses can sometimes also protect against physical damage. You can buy safety glasses that have the UV and HEV protection also, and it's not a bad idea at all to do so. I've had a fly on the end of my line snap hard against a sunglass lens once. Had I not been wearing the sunglasses I'd of had a hook embedded in my eye and I was a good mile of river wading from the closest help. That would have been a disaster of large enough proportion to cause the loss of an eye and a lot of misery.
Choosing good sunglasses is as easy as reading the labels. I could go into a long description of what to look for, but common sense is all you need. Just compare the labels and get the ones that deliver the most protection. Simple enough.
Another advantage for fishermen is when you get polarized lenses - well you don't need me to explain that one to you. Every fisherman knows why polarized are best for fishermen. But just so you know, polarized lenses do not, in and of themselves, automatically also protect against UV. It's probable that when you pick polarized they will also have UV protection, but you need to make sure. The UV protection is far more important than the polarization.
For me, sunglasses are second only to my fly rod as a necessity for fishing.