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How to Tell if Your Sunglasses are Polarised

By Isabella Sara Novack
Reviewed by Beck Jinnette​
Beck Jinnette​

Reviewed by

Beck Jinnette​
Beck has over 17 years of experience in eye care and holds her Certificate IV in Dispensing in Australia.
Learn what polarised lenses are, who they’re for and how to check if your sunglasses are already polarised or not.
sunglasses and eyeglasses on a grey flat surface

Polarised lenses offer the perfect blend of style and protection, serving as your best defence against the harsh light from sun glare. There are many situations in which this is essential as it can greatly enhance both comfort and visual clarity.

Polarisation technologies have been around for a while. First Invented in 1936 by Edwin H. Land, they have now become a standard for certain types of eyewear.

You may even already own a pair of polarised lenses without knowing it! That said, don’t fret: there are a few simple ways to find out if your lenses are polarised or not.  

What are polarised lenses?

Light waves scatter chaotically at different angles when they hit uneven surfaces. When they reach smooth surfaces, like the water’s surface or polished metal,  they reflect neatly in a uniform direction instead.

When bright sunlight strikes a mirror-like surface, the vertical light beams spread out and become horizontally polarised light. We experience these horizontal light rays as glare – a blinding light that can be quite annoying and causes us to squint.

Polarised shades address this issue by filtering out horizontal light. Since they selectively block light traveling in specific directions with a special chemical coating, they are capable of significantly reducing glare and can improve visual clarity and comfort.

This makes wearing polarised lenses ideal for improving visibility and reducing eye strain in bright environments, especially around reflective surfaces. 

How to tell if sunglasses are polarised

If you think polarised glasses would be a good match for your lifestyle but aren’t sure if your current ones have polarisation or not, you’ve come to the right place. Follow these steps to determine if a pair of sunglasses has a polarisation filter.

Compare your polarised sunglasses to others

infographic on how to test if lenses are polarized against a pair of known polarized sunglasses

If you already have a pair of sunglasses that you know are polarised, you can use them for a comparison test. This is how:

  • Take out your two pairs of sunglasses and hold the pair you’re testing close to you. Place the other pair on a flat surface further away, ideally 2.5 to 5.1 cm apart. Make sure the pair you’re testing is nearest to your eyes, with the polarised lens positioned further away.
  • Align the lenses so you can look through both at the same time, but be careful not to let them touch to avoid scratching the coatings.
  • Look through both sunglasses and tilt the polarised pair 90°. When two polarised lenses overlap at opposing angles, they create an almost pitch-black surface. If You can’t see anything through the lenses, then you’ll know they’re polarised. Otherwise, they’re regular sunglasses.

Test them on a reflective surface

You can use a reflective surface, like a shiny tabletop or a body of water, to test if lenses are polarised or not. Follow these steps:

  • Hold your sunglasses approximately 15 to 20 cm in front of your eyes. Make sure you can see the reflective surface through one of the lenses.
  • Rotate the sunglasses to a 90-degree angle..
  • Adjust the angle of your sunglasses if the initial position doesn’t reduce the glare. Observe the glare through the lens as you hold your sunglasses at the adjusted angle. If your sunglasses are polarised, you should notice much less glare.

Look at a screen through your lenses

Digital LED screens and LCD displays (like computer screens or smartphones) have anti-glare technology that can be useful to identify polarised sunglasses. This is how:

how to test polarization of sunglasses against a computer screen
  • Adjust your electronic device to its brightest setting and display a white screen. Put on your sunglasses and hold your device  at eye level. For accurate results, it’s important to face the screen directly. 
  • Tilt your head 60°. While looking directly at the screen, gently tilt your head to the left or right. This action changes the angle at which the polarised light from the screen interacts with your sunglasses.
  • If your sunglasses are polarised, the screen will likely darken significantly or turn black as you move your head. A lack of any significant change instead indicates that there’s no polarisation on the lenses.

Since they cut down the glare from the light reflecting off the water, polarised sunglasses can help fishermen easily spot fish under the surface.

Wearing polarised vs non-polarised sunglasses

Wearing polarised sunglasses offers a significant advantage in environments where glare is a common issue. This is because polarised lenses are specifically designed to block glare when aligned correctly with the direction of the reflected light.

Their ability to reduce glare allows them not only to improve visibility, but also increases contrast and colour perception. This leads to enhanced visual clarity while also helping minimise eye strain on sunny days.

This makes polarised lenses especially beneficial to those who spend time in bright sunlight, for example people who like playing outdoor sports. The relief from constant squinting can make activities like driving, fishing and skiing safer and much more enjoyable.

That said, the use of polarised sunglasses is not without its drawbacks. One notable disadvantage is their performance in low light conditions, where they can significantly reduce visibility. Due to the polarisation filter, wearers may even struggle to distinguish between light colours.

pros and cons infographic of polarised lenses

Additionally, polarisation can cause difficulties when viewing LED and LCD screens. Because of how polarised sunglasses work, it can be challenging to read screen displays (like a computer monitor), GPS devices, or instrument panels while wearing them.

They are also more expensive than their non-polarised counterparts, though for many, the eye health benefits, visual comfort and protection provided by polarised lenses outweigh the drawbacks. 

Alternatives include photochromic and standard tinted lenses for overall brightness reduction and protection from UV light

Blue light glasses are also a good option for people who spend a lot of time looking at a computer screen. These are non-polarised lenses that apply different technologies and can work better for lcd screens and artificial light related eye strain. 

Make the right choice for you

When deciding for or against polarised lenses, it’s important to consider your own lifestyle. The best eyewear not only protects your vision but also aligns with your daily needs to improve your quality of life.

Don’t hesitate to ask our opticians if you have any questions about polarised sunglasses or any other type of lens. And if you do think that polarisation is the right fit? Test your sunglasses to find out if you need to keep your eyes open for a good pair.

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