What Are Polarised Sunglasses? How They Differ From Regular Lenses and Who They Suit

The short answer to what polarised glasses are: polarised sunglasses have a special filter in the lens that removes glare reflected off flat surfaces such as water, wet roads and snow. A regular sun lens only reduces light, while a polarised lens also picks out the dazzling reflection. It makes a noticeable difference to comfort by the sea and on long drives, but on its own it does not mean UV protection.

What are polarised glasses?

Polarised glasses are sunglasses with a polarising filter in the lens that removes reflected glare. This filter is a very thin layer built into the lens or applied to its surface, and you cannot see it from the outside.

It is more accurate to define it through the lens: a polarised lens filters the horizontally polarised light reflected off flat surfaces such as water, wet roads, snow and the bonnet of a car. This glare is different from looking straight at the sun. Even when you are not looking at the sun, it is the white, intense shimmer that reaches your eyes from the surface of the sea or wet asphalt. It makes you squint and hides the detail beneath or beyond the surface.

Polarisation is not a lens colour or a level of darkness. A grey, brown or green lens may or may not be polarised. In the same way, whether a lens is light or dark does not tell you whether it is polarised.

How does a polarised lens work?

A polarised lens works by blocking light that vibrates horizontally and letting the rest of the light through. To understand this, it is enough to look at how light changes when it is reflected:

1. Sunlight reaches the eye as waves vibrating in every direction.
2. When this light hits a flat surface such as water, a road or snow and is reflected, most of it starts vibrating horizontally. The eye perceives this as glare.
3. The filter in the lens behaves like a grille with vertical bars: it blocks horizontally vibrating light and lets other light through.
4. As a result, the rest of the view darkens only as much as the lens tint, while the bright reflection on the surface is reduced much more.

That is why, when you look at the sea through a polarised lens, the shimmer on the surface is reduced and the colour of the water and the shape of the waves are easier to make out. A similar effect appears on the road: because the glare from wet asphalt and the bonnets of the cars ahead is reduced, lane markings and the road surface are easier to see.

Because the filter works in one direction, its effect decreases when you tilt your head to the side. This is also why the polarisation test is done by turning the glasses.

What is the difference between a polarised lens and a regular lens?

The basic difference between a polarised and a non-polarised lens is what they do to reflected glare: a regular lens dims all light equally, while a polarised lens also filters out reflected glare. Even when both have the same tint, the view they give by the sea or on a wet road is different.

The fourth row of the table is the point most often confused, and it is explained under a separate heading below. The darkness side is independent of polarisation: how much light a lens lets through is set by the sunglass filter category, while how colours look is affected by the lens colour.

Who are polarised glasses suitable for?

Polarised glasses suit people who often face reflected glare by the water, on the road or in the snow. The main places they stand out are:

• Sea and beach: the surface of the sea and wet sand reflect the sun strongly. If you squint when looking at the water on the Antalya coast or the beaches of Belek and Kadriye at midday in summer, this is where you will first notice the difference a polarised lens makes.
• Boats and water sports: on the open sea, glare comes from every direction. A polarised lens makes it easier to watch the water surface.
• Fishing: when the reflection on the surface is reduced, it is easier to see below the water. This is why anglers prefer polarised lenses.
• Long drives: wet asphalt and the bonnets and windows of the cars ahead constantly reflect light. A polarised lens reduces these reflections. The details of choosing lenses for driving are covered in our article on sunglasses for driving.
• Snow: a snow surface is also a flat, bright reflector, and a polarised lens filters the glare there too.

For someone who rarely encounters glare and wears their glasses mostly in town and in the shade, polarisation is not essential. In that case the choice comes down to habit and personal preference.

What are the limits of polarised lenses?

The main limit of polarised lenses is that some LCD screens look dark or tinted at certain angles. This is because screens also emit polarised light: when the direction of the screen's light and the filter in the lens do not line up, the image goes dark.

In daily life you may come across this in the following situations:

• The car dashboard and infotainment screen can look faded or dark. The same effect can occur with head-up displays.
• A phone screen can go dark depending on whether you hold it horizontally or vertically.
• The screens of cash machines, fuel pumps and similar devices can be hard to read from certain angles.
• Coloured patterns or ripples may be noticeable in some car windows and glass surfaces.

Polarised lenses are not the first choice for every sport either. In golf, polarised lenses are a personal preference; some players feel they affect reading the slope on the green and depth perception.

How do you test whether a lens is polarised?

Whether a lens is polarised can be found out by looking at an LCD screen through the glasses and turning them 90 degrees. The test is easy to do at home:

1. Switch on an LCD screen such as a phone, computer or television and choose a light, bright image.
2. Put on the glasses, or hold one of the lenses in front of your eye, and look at the screen.
3. Slowly turn the glasses 90 degrees.
4. If the screen goes clearly dark, the lens is polarised. If nothing changes, the lens is not polarised.

If you have a second pair that you know is polarised, you can also try it without a screen: hold the two lenses one over the other and turn one of them 90 degrees; if the view goes dark, both lenses are polarised.

Many glasses have the word polarised printed in a corner of the lens or on the inside of the temple. Even so, doing the test is more reliable than trusting the print; because the angle at which a screen darkens can vary with the type of screen, try again with another screen if the result is unclear.

Do polarised glasses provide UV protection?

No, being polarised does not mean UV protection; polarisation and UV protection are separate features, and one does not indicate the other. The polarising filter removes visible reflection. What blocks ultraviolet light is the UV filter in the lens, and this filter can even be colourless.

For UV protection, look at the label. The UV400 label means the lens does not let through ultraviolet light up to 400 nanometres, which covers almost all UVA and UVB. In Türkiye and the EU, non-prescription sunglasses count as personal protective equipment and carry the CE mark. The details are explained in our article what does UV400 mean.

What should you check when choosing polarised glasses?

When choosing polarised glasses, check the UV400 label and the CE mark first, then the filter category, the lens colour and where you will wear the glasses most. You can check them in order:

1. UV protection: the label should show UV400 and the CE mark. The word polarised does not replace them.
2. Filter category: category 3 lenses are used for strong sun, the beach and the sea. On most glasses the category number is printed on the inside of the temple, next to the CE mark.
3. Lens colour: grey reduces light without changing colours. Brown and amber lenses increase contrast and are preferred in changing light and for driving.
4. Screen compatibility: make sure you can read your phone and your car's dashboard through the glasses.
5. Lens material: polycarbonate lenses are light and impact-resistant; mineral glass lenses resist scratches better but are heavier.

In a region like Antalya, with long summers and strong sun, glasses stay on your face for most of the day. So as well as the properties of the lens, how well the frame fits your face and whether it presses on your nose or behind your ears are part of the choice. A polarised lens helps reduce glare on days spent by the sea; UV protection, however, is shown by the UV400 label.