They allow you look through the surface glare thereby enabling you to see whats going on under the surface.You will need a hat with a brim such as a baseball cap as you need to cut down as much light to your eyes from above and the side.
Be patient, stay quiet and concealed and your fishing will improve.
Are they worth the money? they WILL catch you more fish therfore they are.Optix make excellent ones.
I couldn't imagine spring summer and even autumn and winter fishing without mine.I carry a spare pair they are that important to me.