Paul, definately go with the polarised glasses as other have recommended.
Go for glass over polycarb, harder to scratch and have better optical correctness - this makes a difference when you are moving your head around a lot to reduce eyestrain, such as repetitive casting and getting thrown around in a boat!
Of all the lens colours, I've found the brown / amber lenses to give much better glare reduction and surface penetration (ability to see below the water). Admitedly, they are not always as dark as some of the green / grey lenses, but I have never found myself wanting more sun shade protection with them.
With regard to styles, open sided glases can let in some unwanted light which can bounce of the back of the lens (normally at sinrise or sunset), however blinkered glasses (with a solid sideflap) can impede peripheral vision. This can be an issue in spotting action in the side of your vision, particular on a boat with a few people casting in close quarters. I like to see when the guy beside me is winding up for a back cast out the corner of my eye...if you know what I mean. Generally, glass lenses dont come in wrap around designs unless they are faceted...so you will look like a knob down at the local shops, if this is an issue to you!
Iv'e been using the amber lense Mako's for a few years now (in a regular style) and can't fault them. Teamed up with a hat and buff, I manage to keep most unwanted light out from behind as well. Cheers.
