Just like regular sunglasses, polarised sunglasses protect your eyes from UV.
But, they also have a secondary benefit of being able to filter-out unpolarised sunlight. This can vastly improve your visual clarity and give much greater definition. Non-polarised sunglasses don’t have this feature, which is the main difference between these types of lenses.
So what exactly does this mean for you and why is this such a big deal?
In this article, we’ve delved into the science of polarised lenses to simply explain how these lenses work and how they can change your sunglasses wearing experience.
Why are polarised sunglasses better?
Regardless of frame style, the main goal of your sunglasses is to improve your visual clarity when you’re out in the sun. Right?
But due to the irregular behaviour of sunlight, regular non-polarised lenses have difficulty in controlling and filtering sunlight as it enters the lens.
When sunlight beams towards the ground, it’s neatly aligned and travelling in the same linear direction. But, as it meets molecules in the air it becomes all disorganised and is no longer aligned. It becomes scattered.
Those damn molecules...
This scattering results in irregular angles of light which is otherwise known as unpolarised light.
For regular lenses, unpolarised light results in reduced visual clarity and loss of definition due to the highs and lows of the scattered light.
This is why polarised lenses are deemed as being better, simply because they aren’t as badly affected by unpolarised light.
Struggle to find sunglasses that suit you?
Polarised lenses can filter sunlight, depending on it’s angle of orientation.
This is beneficial in two ways; it can filter scattered sunlight in the air and reflected sunlight when it bounces off horizontal surfaces.
As mentioned earlier, sunlight becomes scattered and with irregular orientations as it bounces of molecules in the atmosphere.
These orientations of light can be any angle within 360° which creates an inconsistent viewing experience, something similar to white noise.
Polarised lenses are able to filter-out sunlight which isn’t vertically aligned which “cleans-up” your visual experience, giving you far more consistent visual clarity.
2. Horizontal light
Ok, so horizontally orientated light can happen in the air.
But when sunlight meets land or sea, it becomes reflected and almost always horizontally orientated. Otherwise called glare, the sunlight has now become condensed and intensified which makes it blindingly difficult to see.
Because polarised lenses block most angles of horizontal light, they eliminate nearly all of this nasty glare.
Out near water or snow, this is a huge benefit as the land around you is reflecting glare towards you like gigantic mirrors.
How do polarised sunglasses work physics?
You’re probably wondering how polarised lenses can block glare.
Especially since they can look exactly the same as ordinary lenses. So here’s the science bit.
Polarised lenses contain a chemical film on their surface or sandwiched within the layers of the lens. This layer is called a polariser, which you must remember is a secondary function to any sun lens.
Upon the polariser are hundreds of chemically aligned molecules in neat little rows. These rows create vertical slots through which light can pass, only if it's orientated parallel to these rows.
When the lens is cut and fitted to your sunglasses frame, these rows must be positioned so they are vertical in your frame.
By doing so, this vertical alignment prevents any horizontal light from entering through your sunglasses which drastically reduces glare from flat reflective surfaces.
In the comparison below, we’ve illustrated scattered light at different angles as it enters a sun lens. Some of the light is vertical, the rest is random.
The right lens appears slightly darker but far more consistent. This is the polariser has blocked the light which isn’t vertical to reduce the glare seen on the left of the illustration.
So what are polarised sunglasses going to do for me?
Reflected sunlight from your car bonnet, water, snow or ice are usually horizontally orientated.
When you're out and about, these are the most common causes for glare.
These large shiny surfaces reflect large amounts of sunlight acting like a very large mirror which produces dazzling horizontally aligned light.
By reducing reflected glare, polarised sun lenses are a superior option for prolonged visual focus which makes them perfect for driving glasses.
It's these benefits that's popularised polarised sunglasses for fishing, skiing, sailing or cycling when glare can detract from physicical performance and lead to visual fatigue.
Are polarised sunglasses better for you?
The main thing to remember is that polarised lenses aren’t any better at providing protection from the sun.
The polariser-layer is simply a way to improve visual clarity by filtering-out horizontally orientated light from the air above or from reflected glare via land/water.
However, this filtration certainly has its benefits.
For context, polarised sunglasses are especially popular amongst sports-people as they minimise distraction from glare. The improvement of clarity helps them focus for long periods of time, especially in high-exposure scenarios such as sailing, running, hiking, cycling or climbing.
But for the average-Joe, you can certainly reap the rewards of this premium lens-type.
All year round, casual strolls or daily driving commutes are unavoidably going to expose you to glare and bright sunlight. Summer or winter commutes can throw all kinds of reflected light at you which regular sun lenses simply don't filter out.
Over time, this glare can lead to eye fatigue which isn’t pleasant if you’re out trying to enjoy the nicer weather or simply drive somewhere in bright conditions.
Fundamentally, polarised sunglasses can block nearly all reflected which is going to keep your vision more consistent and under less strain.
Disadvantages of polarised sunglasses
As good as they are, 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 petrol station screen can be hindered with polarised sunglasses.
To remedy this issue, you might want to take your sunglasses off or look over/under the lens to see properly which might be a little annoying at first.
Regardless of your lifestyle, polarised sunglasses give you uninterrupted clarity on bright sunny days.
Assuredly, polarised lenses are a popular choice amongst active sports people who spend long periods near water or snow. The double whammy of reflected light is a good reason for sailors and skiers to opt for this type of lens.
But, are polarised lenses worth it for the average Joe?
You don’t have to be sailing a transatlantic voyage to notice the benefits of polarised sunglasses. Even on a casual holiday or walking in the sun, the benefits of polarised lenses will help you enjoy your well-earned holiday in full glory.
Don’t forget, regular sun lenses still protect your eyes from UV light.
But whilst regular sunglasses work fine, they’re simply… regular.
On the other hand, polarised sunglasses means you’ll benefit from superior optical clarity, uninterrupted from glare. Frankly, these lenses are the superior choice for prolonged outdoor activities in the sun.
Furthermore, they’re becoming an increasingly popular choice for driving as they reduce distracting summer glare or low-level winter sun.
For more adventurous activities such as skiing, sailing and cycling, polarised lenses are perfect for filtering harsh reflections from snow, ice and water.
Thanks to their multi-layer construction, these super sun-lenses are more efficient for blocking-out polarised sunlight.
Sounds good right?
Long drives mean long periods of concentration.
If you spend a lot of time behind the wheel, polarised sunglasses are going to alleviate your visual fatigue.
With less glare and distracting reflections from the road ahead, polarised lenses help to reduce the amount of strain being placed on your eyes. Ultimately, these sun-lenses are going to help you to focus on the road over long journeys.
Polarised sunglasses are often related to sporting scenarios but driving is a far more common and relatable application.
If there’s one reason to invest in polarised lenses, driving is certainly the most common.
As polarised sunlight enters our atmosphere, it reflects off molecules in the air and can become distorted from the earth's magnetic field.
When this happens, some of the light is re-orientated and is no longer travelling on a linear path, thus becoming unpolarised.
Regular sunglasses aren’t so good at handling unpolarised light, simply because they're unable to filter-out the highs and lows of condensed sunlight from horizontal glare.
During tasks such as driving, this inconsistency can place strain on your eyes as you try to focus which can eventually lead to visual fatigue and even headaches.
This is why polarised sunglasses have their name as they can filter-out the unpolarised, non-vertical light so it's entering your eyes in an organised, filtered manner.
These lenses provide you with a far greater view and consistently give an uninterrupted viewing experience, free from glare.
Besides being more effective to reduce glare, polarised sun lenses can a beneficial for certain ocular ailments.
Polarised sunglasses can help to mitigate the effects of strong sunlight by reducing the amount of light entering your eye.
These benefits are particularly beneficial for those who are trying to let their eyes recover from recent surgery. As a means of self-protection, your eyes can become light sensitive as a result of trauma.
What are polarised sunglasses doing to my phone?
Yea, about that…
Due to the chemical film inside polarised lenses, they can also filter the light from liquid crystal display's (LCD's).
Depending on the make of certain mobile phones, the light they emit can be blocked by polarised sunglasses.
This means your phone screen can look distorted or blackened, depending on the brand and it's age.
If you happen to experience this distortion or screen-blackening, you've got a couple of options to get around this issue.
Modern screen, modern viewing.
LCD technology has improved over the years, without us even realising it.
Updated filters in most modern phones are now far more compatible with polarised sunglasses.
Previously, most phones were fitted with an in-built polariser to reduce glare and reflections in bright sunlight.
This worked great... unless you were wearing polarised sunglasses.
Since about 2015, modern phone companies changed these polarisers which are now far more compatible with your sunglasses.
The best polarised sunglasses test
Polarised lenses look pretty similar to regular ones.
Here's three handy ways to make sure your lenses are legit.