What are polarised sunglasses?

What are polarised sunglasses

Shop polarised sunglasses


So you’re checking out some new sunglasses.

Looking around, you’ll have seen the option for polarised lenses. But what exactly does that mean when you compare them to regular sunglasses?


Polarised sunglasses use laminated lenses which contain a layer called a polariser. This is a chemical film within the lens which improves visual definition by reducing reflected glare from flat reflective surfaces such as water or glass.


To get a better idea of how these lenses work, scroll down to understand the affects of glare and how it’s blocked by polarised lenses to improve your vision.


Man wearing black polarised sunglasses frame


How do polarised lenses work?

Whilst protecting your eyes from UV light, polarised lenses work by blocking horizontally orientated light from entering the lens. This is how they block glare to improve your detection of colour and contrast through your lenses.

Here comes the science.

When sunlight beams towards the ground, it’s neatly aligned and travelling in the same linear direction.

But when the light hits any flat shiny surfaces such as water, it becomes condensed and horizontally orientated into glare. This makes is difficult to see, even whilst looking through regular sun lenses.

To combat glare, polarised lenses contain a chemical film sandwiched within the layers of the lens construction. Upon the polariser are millions of chemically aligned molecules in neat vertical rows.

These rows create a filter of vertical slots through which only vertically orientated visble light can pass. This prevents any horizontal light from entering through your sunglasses to drastically reduce the effects of glare.

When the lens is cut and fitted to your sunglasses frame, these rows must be positioned so they’re vertical to your face. If the lens was to be at 90 degrees, the filter would then let the glare through.

In the illustration below, you can see you polarised sunglasses can be used in various environments to block reflected glare.


Illustration showing how polarised lenses block glare

"How polarised lenses work" | © Banton Frameworks Ltd | For image sharing enquiries, please contact us.


Do polarised sunglasses have 100 UV protection?

Polarised or not, all CE marked, UV400 sunglasses are thus certified to protect your eyes from 99-100% of all UV light in accordance with international and European law.

This certification is to provide you with the recognisable and necessary protection from the damaging effects of ultraviolet light which would otherwise cause damage to your eyes.

Polarised sun lenses are still UV protective, but they have a secondary benefit of being able to block glare to improve your overall vision when you’re faced with glare.



“UVA and UVB rays can harm our skin and our eyes. The damage to our eyes can include sunburn of the cornea (sometimes called snow blindness), skin aging, macular degeneration, cataracts and skin cancer, so proper protection for our eyes is vital.”

"Trust me, I'm a Doctor" BBC


How can you tell if sunglasses are Polarised?

If you’re buying new sunglasses, check with the retail or ecommerce vendor to ensure they’re rated or labelled with a UV40 or UV400 to ensure sufficient protection.

Illegitimate sunglasses may look dark through a tinted lens due to the reduction of visible light. But without sufficient UV protection, your eyes are being unknowingly frazzled by the invisible UV light pouring through your illegal lenses.

At Banton Frameworks, our handmade sunglasses are fitted with polarised lenses which are 100% UV protective.



Caucasian male wearing black polarised sunglasses and a black Tshirt


What is the use of polarised sunglasses?

Polarised lenses are mainly used to reduce the distortion and visually sapping distraction caused by reflected glare.

By eliminating horizontal light, they help to alleviate eye strain over long periods of visual focus. Furthermore, true colour is easier to detect through a polarised lens which is why their regularly used to improve your vision for activities such as sport or driving.

Reflected sunlight from water or a shiny car bonnet or wet road would otherwise make it difficult to see properly. Polarised sunglasses vastly minimise this glare to improve your ability to detect oncoming potential hazards.

Popular uses of polarised sunglasses include;

  • Sailing
  • Driving
  • Boating
  • Mountaineering
  • Fishing


Polarised sunlight hitting car windscreen


Are polarised sunglasses better for driving?

By reducing glare, polarised lenses can help to reduce visual fatigue on long journeys. This can be helpful on bright days when sunlight is continuously taxing your eyes whilst you focus on the road ahead.



"Polarised sunglasses can be helpful for driving, too, because they reduce glare-causing reflections from flat surfaces, such as the hood of the car or the road's surface”.

Erinn Morgan: Allaboutvision.com


However, your polarised lenses may interfere with your ability to see your dashboard controls or when filling your car with fuel. Notoriously, polarised lenses are known to dim LCD screens which can make them difficult to read.

Polarised sunglasses for driving


Brunette female wearing polarised sunglasses


Disadvantages of polarised sunglasses

Polarised lenses also have their drawbacks.

For the extra performance, they come at a slightly higher cost. According to our market research, they cost an average of 28% more than regular, non-polarised equivalents.

Polarised lenses also have a habit of darkening liquid crystal displays (LCD’s) on digital devices such as phones, bank machines, computers or tablets.

This due to the angle of the light that’s emitted from these devices which can be partially or entirely blocked by the polariser film in polarised lenses. Using your phone or reading a bank machine screen can be hindered by polarised sunglasses.

To remedy this issue, you may want to remove or look over/under the lens to see properly which can be annoying to get used to.

Key points

  • Higher cost than regular sun lenses
  • Can darken LCD screens.


Tortoise polarised sunglasses frame standing upright on white background


How can you tell if sunglasses are polarised?

Regular sun lenses look identical to polarised ones. If you want to check your lenses are definitely polarised, here’s a handy method you can use to make sure they’re legit.

  1. Find a source of unnatural light such as a mobile phone screen.
  2. Hold your sunglasses in front of the screen
  3. Look through one lens and begin to rotate the frame
  4. Check to see if the light changes in brightness
  5. If the light changes, your lenses are polarised

If you’re in a shop, another polarised sunglasses test is to overlap two polarised sunglasses frames. By rotating one of the frames, you’ll block all the light through the overlapping lenses if they are polarised.

This effect happens because the polarisers are at 90 degrees to one another. Little to no light will be able to pass through both lenses.



Polarised sunglasses are great for improving your overall visual definition.

They're slightly more expensive than regular, non-polarised sunglasses but they can block nearly all reflected glare from affecting your vision. For activities such as driving or for sport, the reduction of glare can really help to reduce eye strain over long periods of focus.

Remember that polarised sunglasses can have a dimming effect on LCD screens which can block information from digital displays.

Thanks for taking the time to read this article. 



matte black polarised sunglasses



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