Glare is the enemy in any sight-fishing situation. Without the right sunglasses you are never going to see those fish. Not to mention that many of us struggle to tie knots in light line without some sort of magnification.
As an angler, your eyes are precious and the right eyewear helps to protect them from all manner of nasties. Keep your eyes safe from flying hooks and protect them from the damaging glare of Australia's harsh sun. Keep the spray and the bugs out when your boat is planing across the lake or flat as you are racing to the spot.