🕶️ Polarized sunglasses: how do they work?

On the road, by the water, or even in the mountains, light can sometimes be blinding to the point of straining the eyes and making vision less comfortable. Classic sunglasses reduce light intensity, but polarized models go further: they eliminate some of the bothersome glare. This optical miracle relies on a specific property of light: polarization.

The light we perceive is composed of electromagnetic waves oscillating in all directions. When this light reflects off a flat surface—like water, asphalt, or snow—a large portion of these waves align in a single direction, usually horizontal. It is this "polarized" light that causes glare and reduces contrast in our vision.


Polarized lenses contain a special filter, often made of molecules aligned in a precise direction, like the slats of a miniature Venetian blind. This filter allows vertically oriented light—useful for vision—to pass through while blocking horizontally oriented light responsible for glare. The result: less glare, more contrast, and often sharper color perception.

The effect is particularly striking near water. Without polarized sunglasses, the surface of a lake or the sea acts like a mirror, reflecting much of the light back into our eyes. With a polarizing filter, the glare largely disappears, sometimes even allowing you to see through the water. Fishermen, sailors, and photographers are especially fond of this feature.

On the road, the same principle reduces glare on windshields or wet asphalt. This makes driving more comfortable and can even improve the perception of important details. That's why some polarized sunglasses manufacturers specifically target drivers and cyclists.

However, polarized sunglasses are not ideal in all situations. For example, they can make it harder to read LCD screens, whose light is itself polarized. They may also alter the perception of certain icy surfaces, which isn't always desirable for winter sports.

Their effectiveness also depends on the quality of the filter. Low-end models may simply have a dark tint without real polarization, so it's important to check the label or perform a simple test: when looking at an LCD screen and tilting your head, the image should noticeably darken if the polarization is genuine.