Polarized sunglasses are designed to reduce the glare from surfaces like water, snow, and glass. They can be highly useful for sports, driving, and fishing by helping the participant in these activities to see more clearly, allowing for the avoidance of potential hazards. While they may be somewhat more expensive than conventional sunglasses, some consumers prefer polarized sunglasses because they selectively block out glare, rather than making the whole field of vision dimmer, which can be dangerous in some situations.
The polarized sunglasses are applied in many areas including fishing, driving or something like that. Those used by fishermen have polarized filters with the transmission axis oriented vertically to block the light reflected by the water surface. Note that if the fisherman moves his head up or down the line joining the temples remains horizontal and the sunglasses continue to block the glare. Of course, if he leans his head to one side the filters start to point in the wrong direction.
By the way, they are not only used by fishermen but in all other water-sports. They are also becoming popular with truck drivers and for general outdoor activities. The last five years have seen a jump in their sales and are the fastest growing segment in eyewear. They are the ideal eye protection items for outdoor activities. Therefore, if you always stay outside for a lot time, it is better to wear a pair of polarized sunglasses.