Photochromic and polarized lenses are two of the most popular ways to protect against the sun’s harmful ultraviolet (UV) rays, but there are important differences between the two.

Photochromic lenses automatically get darker in the presence of sunlight, and are often referred to casually as transition lenses or transition glasses.

The big advantage of photochromic lenses is their versatility. People who wear them have essentially a pair of eyeglasses and sunglasses rolled into a single set of frames.

Polarized lenses are primarily used to reduce the sun’s glare. They always come in the form of sunglasses, never eyeglasses, and they don’t transition back and forth.

People often use polarized sunglasses while driving on a bright day, since polarization reduces the glare coming from the road, windshield and other cars.

The big advantage of polarized sunglasses is their ability to improve driver safety and the ability to concentrate on the road.

Polarized sunglasses also can be used to reduce reflections from the surface of water, which makes them very popular for fishing and water-based recreational activities.