On polarized affordable prescription sunglasses online, the filter creates vertical openings for light. Only light rays that approach your eyes vertically can fit through those openings. The lenses block all the horizontal light waves bouncing off a smooth pond or a shiny car hood, for instance.

As a result of this filtering, the image you see with polarized lenses is a bit darker than usual. But objects look crisper and clearer with polarized lenses, and details are easier to see.