Polarized or Not: When It Matters

What polarization does

Light that reflects off a flat surface, such as water, a road, a bonnet or snow, comes back mostly lined up in one direction. A polarized lens has a filter that blocks light lined up that way and lets the rest through. The result is that the hard, white glare off those surfaces drops away while the scene itself stays bright. A plain tinted lens dims everything equally, glare included; it does not single the glare out.

Who gains the most

• Drivers. Glare off a wet road, the car in front and your own dashboard reflected in the windscreen all drop.
• Anglers and boaters. With the surface glare gone you can see into the water. This is the classic use.
• Skiers and beach days. Snow and sand throw back a lot of light; polarization takes the edge off it.
• Anyone bothered by glare. If bright reflections tire your eyes, a polarized lens is the single biggest change you can make.

The trade-offs

The same filter that blocks reflected light also blocks some screens. Many LCD displays, including some car dashboards, petrol pumps, cash machines and older phone screens, emit light lined up one way, so through a polarized lens they look dark, blank or rainbow-patched, especially when you tilt your head. Newer phone screens suffer less, but it still happens. Pilots often avoid polarized lenses for exactly this reason: cockpit instruments and laminated windscreens can look wrong through them. Polarized lenses can also hide the sheen on ice, which some drivers and skiers want to see. And they cost more to make, so the same frame is usually dearer with a polarized lens.

Two tests that tell you

1. The screen test. Look at an LCD screen, such as a laptop or a car display, through the lens and slowly tilt the glasses sideways. If the screen goes dark or patchy at some angle, the lens is polarized. If nothing changes, it is not.
2. The two-lens test. Hold a lens you know is polarized in front of the lens you are testing, and turn one of them a quarter turn. If the overlap goes nearly black, both are polarized.

A dark tint or a mirror coating on its own does not mean polarized; the filter is a separate layer. Polarized lenses are sometimes marked with a small P on the lens, but not always.

What GlareBear says, and does not say

Every GlareBear page takes its lens description from our supplier's data. When that description says polarized, the page says so in the lens section and in the Details table. When it does not, the page says that no polarization or UV rating is given, and we do not add one. We would rather say less than guess. If you need a polarized pair, look for the word on the page, or ask us at [email protected] with the model number before you order.

Do you need it?

For walking around town, a good plain tint is enough and you keep full use of every screen. For time on the water, on the road or on snow, polarization earns its keep. Many people own one of each. Lens colour matters alongside polarization; see lens colours explained, and for looking after a polarized or mirrored lens, how to care for sunglasses.